9. Metals Flashcards
8 physical properties of metals
strong
malleable
ductile
sonorous
shiny when polished
good conductors of electricity and heat
high melting and boiling points
high density
Formula for density
mass (grams)
density = ———————
volume (cm^3)
4 Chemical properties of metals
React with oxygen to form OXIDES
Metal oxides are BASES (neutralise acids, forming salt and water)
Metals form positive ions when they react
For the metals in the numbered groups, the charge on the ion is the same as the group number. But transition elements have variable valency
What is VARIABLE VALENCY?
When elements can form ions with different charges e.g Cu+ / Cu2+
Specific properties of iron and its uses
Iron is malleable and strong
Rusts easily in damp air
Unlike most other metals it’s magnetic
It melts at 1530 degrees c.
- used for gates
Specific properties of sodium
soft (can cut with a knife)
floats on water and reacts with it immediately forming a solution
melts at 98 degrees C
Specific properties of gold and its uses
unreactive
malleable, ductile, looks attractive
quite rare
melts at 1064 degrees C
used for jewellery and precious objects
What does reactive mean?
A reactive element has a strong drive to become a compound so that its atoms gain stable outer shells.
Reaction between sodium and water
What’s formed?
Sodium reacts violently with cold water, whizzing over the surface.
Hydrogen gas and a clear solution of sodium hydroxide are formed
Reaction between calcium and water
What’s formed?
The reaction between calcium and cold water is slower.
Hydrogen bubbles off, and a cloudy solution of calcium hydroxide Ca(OH)2 forms.
Reaction between magnesium and water
What’s formed?
Magnesium reacts very slowly with cold water, but vigorously on heating in steam, it glows brightly.
Hydrogen and solid magnesium oxide MgO form.
Potassium reaction with water
Products
Very violent with cold water catches fire
Hydrogen and a solution of potassium hydroxide, KOH
Zinc reaction with water
Products
Quite slow with steam
Hydrogen and solid zinc oxide ZnO
Iron reaction with water
Products
Slow with steam
Hydrogen and solid iron oxide Fe3O4
Copper, silver, gold reaction with water
Products
no reaction
What is the pattern for the products formed when metals react with water
First 3 produce hydroxides and the rest produce insoluble oxides, if they react at all
magnesium reaction with hydrochloric acid
Products
Vigorous
Hydrogen and a solution of magnesium chloride MgCl2
zinc reaction with hydrochloric acid
Products
quite slow
hydrogen and a solution of zinc chloride ZnCl2
iron reaction with hydrochloric acid
Products
slow
hydrogen and a solution of iron(II) chloride FeCl2
lead reaction with hydrochloric acid
Products
slow, and only if the acid is concentrated
hydrogen and a solution of lead (II) chloride PbCl2
Copper, silver, gold reaction with hydrochloric acid
Products
no reaction, even with concentrated acid
Chemical equation between magnesium and hydrochloric acid
Mg (s) + 2HCl (aq) —> MgCl2 (aq) H2 (g)
What happens during a reaction between a metal and water/hydrochloric acid?
When a metal does react with H2O or HCl, it drives hydrogen out (displaces it) and takes its place. This shows that. the metal is more reactive than hydrogen and has a stronger drive to form a compound.
Is the displacement of hydrogen a redox reaction?
Yes
general explanation of redox reaction between magnesium and hydrochloric acid
When magnesium reacts with hydrochloric acid, its atoms lose electrons (is oxidised). The hydrogen ions from the acid gain electrons (are reduced).
The half equations for the reaction between magnesium and hydrochloric acid
Mg –> Mg2+ + 2e- (oxidation)
2H+ + 2e- –> H2 (reduction)
How is the reactivity series ordered?
Metals are put in order based on their reactivity with water and hydrochloric acid
What happens when MgO is mixed with powdered carbon and heated?
What does this mean?
There’s no reaction
This means magnesium is more reactive than carbon
What happens when PbO is mixed with powdered carbon and heated?
What does this mean?
Equation?
Turns into molten lead and CO2 is formed
Carbon is more reactive than lead
2PbO + C —> 2Pb + CO2
The general rule for carbon reacting with metal oxides
Carbon is more reactive than some metals. It will reduce their oxides (be oxidised itself - its a reducing agent) to form the metals.
What happens when powdered iron is heated with copper (II) oxide CuO?
What does this mean?
The reaction gives out heat and the mixture glows. Iron (II) oxide and copper are formed.
The iron is more reactive and takes the oxygen from copper - displaces it.
The chemical equation between iron and copper (II) oxide?
Fe + CuO —> FeO + Cu
What does the iron act as in the reaction between iron and copper (II) oxide?
A reducing agent - reduces copper but is oxidised itself.
What is the general reaction/rule for when a metal is mixed with a metal oxide?
A metal will reduce the oxide of a less reactive metal. The reduction always gives out heat - it is exothermic.
What happens when an iron nail is placed in a solution of copper (II) sulphate?
What does this mean?
Copper coats the nail. The solution turns green, which indicated iron (II) ions.
Iron has pushed (displaced) copper out of the solution - it is MORE REACTIVE.
What is the chemical equation for the reaction between an iron nail and copper (II) sulphate?
Fe + CuSO4 —> FeSO4 + Cu
What is the general rule for metals competing to form ions in solution?
A metal displaces a less reactive metal from solutions of its compounds.
What is the rule for deciding which metal is oxidised?
The more reactive metal forms positive ions more readily - is oxidised more readily
The more reactive metal will give up electrons to form ions and the less reactive one will accept them to form a solid version of the metal.
List reactivity series
P
S
L
C
M
A
(C)
Z
I
L
(H)
C
S
G
What is the meaning of the reactivity series?
really a list of metals in order of their drive to form positive ions with stable outer shells,.
The more easily its atoms can give up electrons the more reactive the metal will be
How will a metal react with a compound of a less reactive metal?
It’ll react by displacing (pushing out) the less reactive metal out of the compound and taking its place
Relation between reactivity of metal and its compound
the more reactive a metal is the more stable its compounds are. THEY DO NOT BREAK DOWN EASILY
The relation between the reactivity of a metal and its extraction
The more reactive the metal, the more difficult it is to extract from its ores since their compounds are stable.
The relation between the reactivity of a metal and its chance of forming a compound
The less reactive the metal, the less likely it is to form a compound.
What does thermal decomposition mean?
When a compound breaks down on heating
Effect of heat on sodium carbonate, hydroxide, nitrate
1 & 2 - no change in white compound
Nitrate - White compound partly decomposes to nitrite and oxygen
2NaNO3 —> 2NaNO2 + O2
Effect of heat on copper carbonate
The blue-green compound readily breaks down to black copper (III) oxide and carbon dioxide.
CuCO3 —> CuO + CO2
Effect of heat on copper hydroxide
The pale blue compound readily breaks down to copper (II) oxide and water:
Cu(OH)2 —> CuO + H2O
Effect of heat on copper nitrate
The bright blue compound readily breaks down to copper (II) oxide and the brown gas nitrogen oxide.
2Cu(NO3)2 —> 2CuO + 4NO2 + O2
4 General Rules for Thermal Decomposition
The lower a metal is in the reactivity series, the more readily its compounds decompose when heated
Carbonates, (except Na & K) decompose to the oxide and CO2
Hydroxides, (except Na & K) decompose to oxide and H2O
Nitrates (except Na & K) decompose to the oxide, NO2 & CO2. (Nitrates of Na & K form nitrites and oxygen)
Name 4 ways in which we make use of the reactivity series
The thermite process
In making simple cells
In the sacrificial protection of iron
Galvanising
What is the thermite process used for?
To repair rail and tram lines
What two compounds are used in the thermite process?
Powdered aluminium and iron (III) oxide are put in a container over the damaged rail
What happens during the thermite process chemically?
When the mixture is lit, the aluminium reduces the iron (III) oxide to molten iron in a very vigorous reaction.
The iron runs into the cracks and gaps in the rail and hardens.
The chemical equation for the thermite process
Fe2O3 + 2Al —> 2Fe + Al2O3
Look at Making Simple Cells revision aid
yes
Describe the reason why a simple cell works
The difference in reactivity causes a redox reaction that gives out energy in the form of electricity
What does a simple cell consist of?
A simple cell consists of two different metals in an electrolyte.
Which metal is the positive pole in a simple cell? Why?
What’s the other more reactive metal called?
Electrons flow from the more reactive metal, so it is called the negative pole.
The other is the positive pole.
What is the rule for voltage in a simple cell?
The further apart the metals are in reactivity, the higher the voltage will be
What does a voltmeter measure?
Measure the voltage that makes electrons flow
What metals can be used for the sacrificial protection of iron? How is it attached?
zinc, magnesium, etc
anything more reactive than iron
A block of the metal may be welded to the structure e.g a ship
Give the redox reaction for zinc and water (if zinc is used for sacrificial protection and reacts in water)
Oxidation - Zn —> Zn2+ + 2e-
R O2 + 2H2O + 4e- —> 4OH-
Overall equation for zinc used in sacrificial protection
2Zn + O2 + 2H2O —> 2Zn(OH)2
When is galvanising used?
used for the steel in car bodies and the corrugated iron for roofing
What is galvanising?
When iron / steel are coated by zinc
How are car bodies galvanised?
Carried out by a form of electrolysis
How are roofs galvanised?
Iron is dipped in a bath of molten zinc
How is galvanising beneficial?
Zinc coating keeps air and moisture away.
Why is galvanising more effective than sacrificial protection?
In SP, zinc block has to be replaced before it’s dissolved but in galvanising even if the coating is damaged, the iron still won’t be damaged due to SP
How come aluminium is more reactive than iron but is used for things such as satellite dishes, ladders and TV aerials?
Aluminium protects itself
reacts rapidly with oxygen forming a thin coat of aluminium oxide (which you can’t see)
this sticks tight to the metal acting as a barrier to further corrosion, leading to aluminium acting as if it was unreactive
Test for Hydrogen
Squeaky ‘pop’ test
A more reactive metal…
…Will displace a less reactive metal from an aqueous solution of one of its salts.
Ionic Equations
An equation that shows only those ions or atoms that change in a chemical reaction.
Mg + CuSO4 -> MgSO4 + Cu
Mg + Cu2+ -> Mg2+ + Cu
Redox Reactions
The gain and loss of electrons
2 ways of extracting metal from metal ore?
Displacement with carbon
Electrolysis
Pure Metal Atomic Structure
> Organised in closely packed, regularly set out layers.
Contain a sea of free moving, delocalised electrons.
When heated, soft and easily shaped because the layers can easily slip over each other.
Why are alloys harder than the pure metals that they are made of?
Because they usually have controlled amounts of carbon mixed into their structure, which disrupts their regular layout and prevents the layers from sliding over one another.
How are metals held together?
Through stron electrostatic attraction between the free electrons and the positively charged ions.
Shape Memory Alloys
Mixture of metal which responds to changes in temperature.
Properties of copper.
> bendable but strong
> very conductive.
Bronze =
Copper + Tin
Tough and non-corrosive
Brass =
Copper + Zinc
Hard
Aluminium alloys are…
Lightweight but strong, used for aircrafts, armoured tanks etc.
Blast Furnace
The huge reaction vessels used in industry to extract iron from its core.
Components of a blast furnace and their jobs.
> iron ore (haematite)
-iron oxide
-a compound that contains iron
coke
-carbon
-burns in air to produce heat, and reacts to form carbon monoxide (needed to reduce the iron oxide)
limestone
-calcium carbonate
-helps to remove acidic impurities from the iron by reacting with them to form molten slag
air
-oxygen
-allows the coke to burn, and so produces heat and carbon monoxide
Carbon Steels
Alloy of iron containing controlled, small amounts of carbon.
High-Alloy Steels
Expensive alloy of Iron mixed with a relatively large proportion of other metals.
Low-Alloy Steels
Alloy of Iron containing between 1-5% of other metals.
What is a raw material?
A natural resource that can be used to make a useful product.
What is the main ore of iron, which is mainly iron (lll) oxide?
Hematite Fe3O2
What are the four raw materials that go into a blast furnace?
Iron ore (Fe2O3)
Coke (C)
Limestone (CaCo3)
Preheated air
What are the three things that come out of a blast furnace?
Molten iron
Molten slag
Waste gases
What is the most abundant waste gas that comes out and why?
Nitrogen
It makes up 80% of the air that enters the furnace but does not react in the furnace.
Why does molten slag float on top of molten iron?
Its less dense.
How does the fact that molten slag floats on top of molten iron stop the iron reverting to reform iron (lll) oxide?
The molten iron is not in contact with the preheated air so will not get reoxidised by the oxygen in the preheated air.
How is coke produced from the coal?
Heating coal in the absence of air.
Write a chemical equation for the burning of coke in the air
C(s) + O2 (g) —> CO2 (g)
Why is burning of coke in the air important in the blast furnace?
It produces heat for the other reactions in the furnace (which are all endothermic)
Write the word and chemical equation for the decomposition of the limestone
Calcium carbonate —> calcium oxide + carbon dioxide
CaCo3 —> CaO + CO2
Which impurity is removed by calcium oxide?
Silica/silicon dioxide
What is name of the product formed by the reaction of the impurity with calcium oxide?
Slag/calcium silicate
Write a word and chemical equation for the reactions of this impurity with calcium carbonate. What type of reaction is taking place?
Calcium oxide + silicon dioxide —> calcium silicate
CaO + SiO2 —> CaSiO3
Neutralisation
What are the physical properties of iron if the impurity being removed by the limestone were not removed.
The iron would become brittle and break.
Give two uses of slag
Road building - motorways
heat insulation blocks
Where in the blast furnace does the reaction of coke and oxygen take place?
At the bottom where heat enters.
What is the significance of the reaction between coke and oxygen?
It is exothermic and provides heat for the other reactions.
Write a word and chemical equation for the reaction of carbon dioxide with coke
Carbon dioxide + Coke —> Carbon monoxide
CO2 (g) + C(s) —> 2CO(g)
What is the function of the reaction of carbon dioxide with coke (include chemical equation)
Reducing agent
CO removes oxygen from the iron ore
3CO + Fe2O3 —> 2Fe + 3CO2
Explain how the carbon content of the iron from the blast furnace is lowered to produce mild steel
High pressure oxygen is blown into the molten iron. It oxidises the carbon to carbon dioxide which then escapes.
What is an alloy?
A mixture of metals or metals with non-metals
Why is pure iron soft and malleable?
The electrons/ions can slide over one another.
Why does alloying metals make them harder?
Alloying metal atoms are a different size to iron atoms and stop the layers from sliding past each other.
Give a use for:
Stainless steel
Titanium steel
Mild Steel
Hard Steel
Stainless steel - cutlery
Titanium steel - bicycle frames
Mild Steel - car bodies
Hard Steel - chisels
How does iron conduct electricity?
Delocalised electrons that move through the lattice when a potential is applied.
Name the process used to extract aluminium?
Electrolysis
Name the materials used for the electrodes
Graphite (carbon)
What are the polarity of the two electrodes?
Anode = +
Cathode = -
What are the two compounds present in the liquid?
Aluminium oxide (alumina) and cryolite
What is the major cost of the attraction of aluminium?
Electricity
What is the element at the anode?
Oxygen
What is compound formed at the anode and explain how it forms?
Carbon dioxide - the oxygen produced at the anode combines with the carbon anode.
Why is molten aluminium oxide difficult to obtain?
The melting point is extremely high.
Give two reasons why cryolite is used in the electrolysis of aluminium oxide.
to reduce the operating temperature of aluminium
- its a solvent
Write the ionic half equation to show the formation of aluminium at the negative electrode (cathode)
Al^3+ + 3e- —> Al
Write the ionic half equation to show the formation of oxygen at the positive electrode (anode)
2O- - 4e- —> O2
What type of process is the electrolysis of aluminium oxide?
Redox
What is being oxidised in the the ionic half-equations out of the formation of aluminium and oxygen?
The oxides have been oxidised to oxygen molecules (loss electrons)
What is being reduced in the the ionic half-equations out of the formation of aluminium and oxygen?
The aluminium ions have been reduced to aluminium atoms (gaining electrons)
Why do positive electrodes (anode) need replacing regularly?
They are warn out because they are reacting with the oxygen in the air to form carbon dioxide
(C+O2 —> CO2)
Describe the structure of aluminium
A lattice of Al+++ ions hold together by delocalised electrons.
Why is aluminium a good conductor of electricity?
Delocalised electrons/ions can move freely around the structure with potential applied.
What is the main ore of aluminium that is purified to make alumina?
Bauxite Al2O3
Why doesn’t alumina powder conduct electricity?
The ions/electrons are stuck in the lattice unable to move freely.
Why aluminium cannot be extracted using coke in a blast furnace?
Aluminium is more reactive than carbon. Carbon cannot remove the oxygen from the aluminium.
What properties of aluminium are needed for the following:
Aeroplane bodies
Drink cans
Overheated power cables
Pans for cooking food
Aeroplane bodies - low density
Drink cans - malleable
Overheated power cables - conduct electricity
Pans for cooking food - conducts heat well
What is meant by the term malleable?
Can be hammered into sheets
Explain why aluminium is malleable
Layers of aluminium atoms that can slide past each other freely.
What is meant by the term ductile?
Can be drawn out into wire
What is meant by the term alloy?
Metals or non metals and metals mixed together.
Give an example of an aluminium alloy and its use
Magnalium
To make aeroplanes bodies as they have a low density.
Explain why the alloy is stronger than pure aluminium metal
In pure aluminium the atoms are all of the same size so the layers of atoms can slide past each other easily. The atoms of the metals alloyed with aluminium are of a different size. They therefore disrupt the lattice and stop the layers from sliding over each other.
What are the general physical properties of metals?
High density
Good conductors
Malleable
Ductile
High fixed points
What are the general chemical properties of metals?
Form basic oxides
Form positive ions
What are the general chemical properties of metals?
Form basic oxides
Form positive ions
What is an alloy?
A mixture of metals
What is brass made of, its properties and uses?
Copper and zinc
Stronger and more resistant to corrosion
Electrical fittings, car radiators
What is bronze made of, its properties and uses?
Copper and tin
Harder, stronger and sonorous
Statues, springs, coins
What is stainless steel made of, its properties and uses?
Iron, chromium and nickel
Does not rust
Kitchen sinks, cutlery, chemical plant
Why are alloys stronger than metals?
The different sized metal atoms disrupt the crystal lattice and make the arrangement less regular - stops layers of sliding over each other when force is applied
Describe the order of the reactivity series?
K – Potassium
Na – Sodium
Li – Lithium
Ca – Calcium
Mg – Magnesium
Al – Aluminium
C – Carbon
Zn – Zinc
Fe – Iron
Pb – Lead
H – Hydrogen
Cu – Copper
Ag – Silver
Au – Gold
Everything above hydrogen in the reactivity series can
displace hydrogen from its acids
Why does aluminum seem not reactive ?
It forms an oxide layer which adheres to metal and protects it
What are displacement reactions?
reactions in which metals compete for oxygen or anions
The bigger the difference in reactivity between the two metals ___
the faster the displacement reaction
What is the extraction method for metal ores above carbon?
Electrolysis
What is the extraction method for metal ores below carbon and above hydrogen?
Reducing via heating with Carbon or Carbon Monoxide
What is the ore for extracting iron?
haematite
Describe the process of extracting iron from haematite? (6)
1) Coke burns to form CO2 which heats the furnace
2) CO2 reacts with coke to form carbon monoxide
3) Carbon monoxide reduces iron (III) oxide to form iron
4) Heat from furnace decomposes limestone
5) Calcium oxide reacts with silicon (IV) oxide to form slag
6) Slag run off
The more reactive a metal ___ the higher
the tendency of a metal to form its positive ion
What is the ore for extracting zinc?
zinc blende/zinc sulfide
Describe the process of extracting zinc from zinc blende? (6)
1) Zinc blende roasted (with oxygen) to form zinc oxide
2) Zinc oxide heated w/ coke in blast furnace
3) Carbon reacts with oxygen to form carbon monoxide
4) Carbon monoxide reduces zinc oxide to zinc
5) Zinc oxide can also react directly with carbon
6) Zinc vapour carried and condenses and purified
Why is electrolysis of zinc sulfate now preferred over blast furnace method?
Produces purer zinc
Describe the conversion of iron into steel (5)
1) Molten iron from blast furnace poured into steelmaking furnace
2) Oxygen + calcium oxide blown through oxygen lance
3) Oxygen oxidises impurities (carbon, sulfur, silicon, phosphorus) - some escape as gas, some react with calcium oxide to form slag
4) Amount of carbon controlled by oxygen blown, more carbon, less carbon
5) Addition of other metals to form steel
What are the uses of high carbon steel and mild steel?
Mild steel: machinery and car bodies
High carbon steel: knives and blades
What are the advantages of recycling metal? (2)
saves land that may be used for extracting ores
conserves metal ores + raw materials
saves energy, less fuel is used
What are the disadvantages of recycling metal? (2)
collecting and storing materials costly
takes time and energy to collect waste materials
What are the uses of aluminum?
manufacture of aircraft (strength +low density)
food containers (resistance to corrosion)
What are the uses of copper?
electrical wiring
cooking utensils (malleable/good conductor of heat)
What are the uses of zinc?
galvanise iron (stop rusting)
How can different steel alloys be formed/controlled?
Change carbon content
What are three reasons why alloys are used?
Strength
Hardness
Resistance to corrosion
What is the pneumonic for the reactivity series?
Please Stop Calling Me A Cute Zebra I Like Her Call Smart Goat
Why can’t aluminum be extracted by carbon?
Aluminum is too reactive
What is the aluminum ore?
bauxite
What electrodes are used?
Graphite
What is cryolite?
Na3AlF6
Why is molten cryolite used?
To lower the melting point - since electrolytes can’t be kept at high temp. for long
To improve conductivity
What can also be used to further reduce the melting point of the electrolyte?
Calcium Flouride
Describe the process of extracting aluminum (5)
The extraction of aluminum from purified bauxite or aluminum oxide is done through the process of electrolysis. Here are the steps involved in the extraction process:
Preparation of alumina: Bauxite ore is purified to yield a white powder, aluminum oxide, also known as alumina. This is done by crushing the bauxite ore, mixing it with sodium hydroxide, and heating it in a kiln to produce pure alumina.
Preparation of cryolite: The pure alumina is then mixed with cryolite, a mineral that acts as a solvent for alumina and lowers its melting point.
Electrolysis: The alumina-cryolite mixture is then dissolved in a large electrolytic cell, which is made of steel and lined with carbon. Carbon anodes are immersed in the electrolyte, and a large graphite cathode is suspended in the center of the cell.
Electrical current: A direct current is passed through the cell, causing the alumina to break down into aluminum ions and oxygen ions. The aluminum ions are attracted to the cathode, where they gain electrons and form molten aluminum metal. The oxygen ions react with the carbon anodes to form carbon dioxide gas.
Collection of aluminum: The molten aluminum is then siphoned off and transferred to holding tanks, where it solidifies into aluminum ingots.
Recycling: The remaining electrolyte, which contains dissolved alumina and cryolite, is pumped out of the cell and recycled for use in the next batch of alumina.
Overall, the extraction of aluminum from purified bauxite or aluminum oxide involves a complex process of electrolysis, which requires a large amount of electrical energy and specialized equipment. However, this process is essential for the production of aluminum, which is a versatile and important metal used in a wide range of applications, from aircraft manufacturing to packaging materials.
Write all the equations involved in extracting aluminum (4)
Potassium
Sodium
Calcium
Magnesium
Note that metals such as zinc, iron, copper, and silver are not reactive enough to react with cold water.
What forms at the cathode?
Aluminium
What forms at the anode?
Oxygen
What is the main ore of iron?
Hematite (Iron III Oxide)
What is the temperature at the bottom and top of the furnace?
1500 degrees celsius
250 degrees celsius
What are the raw materials involved in extracting iron? (4)
hematite, air, coke, limestone
What is the main reducing agent in extracting iron?
carbon monoxide
What kind of reaction is coke burning hot air?
exothermic - heat released keeps furnace heated
Describe the process of extracting iron (5)
(a) Burning of carbon (coke) to provide heat and produce carbon dioxide:
Coke is burned in the blast furnace to provide the heat required for the extraction of iron. The carbon in the coke reacts with the oxygen in the air to produce carbon dioxide and heat.
(b) Reduction of carbon dioxide to carbon monoxide:
Carbon dioxide produced from the combustion of coke is reduced to carbon monoxide by passing it through hot coke.
(c) Reduction of iron(III) oxide by carbon monoxide:
The carbon monoxide produced in step (b) is then used to reduce the iron(III) oxide in the hematite ore to iron metal. The reaction can be represented by the following equation:
Fe2O3 + 3CO → 2Fe + 3CO2
(d) Thermal decomposition of calcium carbonate/limestone to produce calcium oxide:
Limestone (calcium carbonate) is added to the furnace to help remove impurities in the ore. When heated, it decomposes to produce calcium oxide and carbon dioxide.
CaCO3 → CaO + CO2
(e) Formation of slag:
The impurities in the ore react with the calcium oxide to form a molten slag, which is less dense than the molten iron and floats on top of it. The slag is then removed from the furnace.
Overall, the extraction of iron from hematite ore in the blast furnace involves the burning of coke to provide heat and produce carbon dioxide, reduction of carbon dioxide to carbon monoxide, reduction of iron(III) oxide by carbon monoxide, thermal decomposition of calcium carbonate/limestone to produce calcium oxide, and the formation of slag.
Write all of the equations involved in extracting iron (6)
(a) C + O2 → CO2
(b) C + CO2 → 2CO
(c) Fe2O3 + 3CO → 2Fe + 3CO2
(d) CaCO3 → CaO + CO2
(e) CaO + SiO2 → CaSiO3
What is slag?
calcium silicate
What is solid slag used in?
road building
What is solid slag used in?
road building
compare the thermal conductivity metals vs non metals
metals- good conductor of heat
non-metals- poor conductor
Explain in terms of structure in metals why they are malleable
this is because the layers of +ive ions can slide over each other making it easy
compare the electrical conductivity metals vs non metals
metals- great conductors
non metals- poor conductors
compare the physical properties of non metals vs metals
metals- maellable, ductile, shiny
non metals- quite brittle, not ductile not malleable
How come metals are able to conduct electricity well?
due to presence of free moving electrons
describe structure of metals
giant 3 dimensional structure in which regular rows of positive ions are surrounded by ‘sea’ of free moving electrons
do metals have low or high m.p and b.p
generally high
compare the electrical conductivity metals vs non metals
metals- great conductors
non metals- poor conductors
How come metals are able to conduct electricity well?
due to presence of free moving electrons
describe structure of metals
giant 3 dimensional structure in which regular rows of positive ions are surrounded by ‘sea’ of free moving electrons
do metals have low or high m.p and b.p
generally high
how come that metals have generally high m.p and b.p?
because of the strong metallic bonds between molecules
what is the product when we react a metal with oxygen?
a metal oxide
metal+ oxygen—–>?
metal oxide
what are the reactants that create the product of an oxide
metal+oxygen
metal+ cold water——>?
hydroxide+ hydrogen gas
name the metals that can react with cold water
sodium, calcium and potassium
metal+ steam——>?
metal oxide+ hydrogen gas
what is the gas produced when we react a metal with steam?
hydrogen
what is the gas produced when we react a metal with cold water?
hydrogen
metal+acid——>?
salt+ hydrogen
explain the reaction of metals + acids
when they react, hydrogen atom in acid is replaced by metal atom to produce a salt and hydrogen gas
name the gas produced when a metal and an acid react together
hydrogen
what kind of metals do NOT react with oxygen, name two
the unreactive metals; AG and AU, gold and silver
what kind of metals react with oxygen really easily?
alkali metals
Why is aluminium used in the manufacturing of aircraft?
because of it’s low density
Why is aluminium used in the manufacture of overhead
electrical cables?
because of its low density
and good electrical conductivity
Why is aluminium used in food containers?
because of its resistance to corrosion
Why is copper used in electrical wiring?
because of its good electrical conductivity and ductility
What is an alloy?
a mixture of a metal with other elements
What is brass a mixture of?
copper and zinc
what is brass described as and why?
as an alloy because it is made up of a mixture of a metal with other elements
What is stainless steel a mixture of?
mixture of iron and other
elements such as chromium, nickel and
carbon
Are alloys better than pure metals? why?
alloys can be harder and stronger than
the pure metals and are more useful
Explain in terms of structure how alloys can
be harder and stronger than the pure metals
Alloys contain atoms of different sizes, which distorts the normally regular arrangements of atoms in metals
This makes it more difficult for the layers to slide over each other, so alloys are usually much harder than the pure metal
Describe the uses of alloys in terms of their
physical properties, including stainless steel
in cutlery because of its hardness and resistance to
rusting
State the order of the reactivity series
potassium, sodium, calcium, magnesium,
aluminium, carbon, zinc, iron, hydrogen, copper,
silver, gold
is an alloy a compound?
no, Alloys are mixtures of substances, they are not chemically combined and an alloy is not a compound.
Why is stainless steel used in cutlery?
Stainless steel is the most durable and long-lasting cutlery material, perfect for everyday use. It is strong even at high temperatures, resistant to water and washing in dishwashers. Another benefit is it’s easy to care for and keeps a lasting shine and corrosion resistant, and it doesn’t affect the flavour of the food when used for food storage or production. Due to the resistance level, foods with high acidity won’t cause damage.
Describe the relative reactivities of metals in
terms of their tendency to form positive ions, by
displacement reactions, if any, with the aqueous
ions of magnesium, zinc, iron, copper and silver
a metal higher up on this reactivity series can displace any metal below it in a single displacement reaction.
For example, potassium (K) can displace magnesium (Mg), zinc (Zn), iron (Fe), copper (Cu), and silver (Ag) from their aqueous solutions in single displacement reactions.
However, silver (Ag) cannot displace any of the metals above it from their aqueous solutions.
To illustrate this, consider the reaction between copper (Cu) and silver nitrate (AgNO3). Copper is less reactive than silver, so it cannot displace silver from its aqueous solution:
Cu(s) + 2AgNO3(aq) → no reaction
On the other hand, if we take zinc and copper sulfate, zinc is more reactive than copper, so it can displace copper from its aqueous solution:
Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)
Why does potassium react with cold water the way it does?
This reaction occurs because potassium is highly reactive and has a strong tendency to lose its outermost electron, which reacts with water to produce hydrogen gas and hydroxide ions.
what is the reaction of potassium with cold water?
undergoes a violent and exothermic reaction, producing potassium hydroxide (KOH) and hydrogen gas (H2):
2K(s) + 2H2O(l) → 2KOH(aq) + H2(g)
Why does sodium react with cold water in such way? / what reacts more vigorous with cold water out of the reactivity series?
The reaction of sodium with cold water is similar to the reaction of potassium with cold water, as both metals are highly reactive alkali metals that readily lose their outermost electrons to form cations. However, the reaction of sodium with water is not as violent as the reaction of potassium with water. Nonetheless, the reaction can produce enough heat to ignite the hydrogen gas produced, so it should not be performed without proper safety precautions.
what is the reaction of sodium with cold water?
undergoes a highly exothermic and vigorous reaction, producing sodium hydroxide (NaOH) and hydrogen gas (H2):
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
what is the reaction of calcium with cold water?
undergoes a less vigorous reaction compared to sodium and potassium, producing calcium hydroxide (Ca(OH)2) and hydrogen gas (H2):
Ca(s) + 2H2O(l) → Ca(OH)2(aq) + H2(g)
Calcium is less reactive than sodium and potassium, but it still has a strong tendency to lose its outermost electrons, which reacts with water to produce hydrogen gas and hydroxide ions. The calcium hydroxide produced is slightly soluble in water, forming a white precipitate.
what is the reaction of magnesium with steam like
it undergoes a displacement reaction, producing magnesium oxide (MgO) and hydrogen gas (H2):
Mg(s) + H2O(g) → MgO(s) + H2(g)
The reaction of magnesium with steam is an example of a metal reacting with a non-metal oxide to produce a metal oxide and a gas. The reaction occurs because magnesium has a strong tendency to lose its outermost electrons, which can then react with the oxygen in steam to form magnesium oxide. The hydrogen gas is produced as a byproduct of the reaction.
reaction of HCL with magneisum
When hydrochloric acid (HCl) is added to magnesium (Mg), a single displacement reaction takes place, producing magnesium chloride (MgCl2) and hydrogen gas (H2):
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
The reaction between HCl and magnesium is an example of an acid-metal reaction, where the acid donates hydrogen ions to the metal to form a salt and hydrogen gas. The hydrogen gas is produced as a byproduct of the reaction and can be observed as bubbles in the solution. The reaction between HCl and magnesium is exothermic and produces heat, but the reaction is not as violent as the reaction between metals like sodium and potassium with acids.
reaction of HCL with zinc
When hydrochloric acid (HCl) is added to zinc (Zn), a single displacement reaction takes place, producing zinc chloride (ZnCl2) and hydrogen gas (H2):
Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)
The reaction between HCl and zinc is an example of an acid-metal reaction, where the acid donates hydrogen ions to the metal to form a salt and hydrogen gas. The hydrogen gas is produced as a byproduct of the reaction and can be observed as bubbles in the solution. The reaction between HCl and zinc is exothermic and produces heat, but the reaction is not as violent as the reaction between metals like sodium and potassium with acids.
reaction of HCL with iron
When hydrochloric acid (HCl) is added to iron (Fe), a single displacement reaction takes place, producing iron (II) chloride (FeCl2) and hydrogen gas (H2):
Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g)
The reaction between HCl and iron is an example of an acid-metal reaction, where the acid donates hydrogen ions to the metal to form a salt and hydrogen gas. The hydrogen gas is produced as a byproduct of the reaction and can be observed as bubbles in the solution. The reaction between HCl and iron is exothermic and produces heat, but the reaction is not as violent as the reaction between metals like sodium and potassium with acids. Iron (II) chloride is a greenish-yellow solid that is soluble in water.
reaction of HCL with copper
When hydrochloric acid (HCl) is added to copper (Cu), no visible reaction occurs. Copper is not reactive enough to displace the hydrogen ions in HCl to form a copper chloride salt and hydrogen gas.
Copper is less reactive than hydrogen, so it cannot replace hydrogen in hydrochloric acid. Therefore, copper does not react with hydrochloric acid under normal conditions. However, if the concentration of the hydrochloric acid is increased or the temperature is raised, a slow reaction may occur with the formation of copper (II) chloride (CuCl2) and hydrogen gas (H2):
Cu(s) + 2HCl(aq) → CuCl2(aq) + H2(g)
It is important to note that this reaction is not as common or practical as the other reactions of HCl with metals, as copper is generally not used as a reactive metal due to its low reactivity.
reaction of HCL with gold
Gold (Au) is a noble metal and is unreactive towards most acids, including hydrochloric acid (HCl). As such, there is no visible reaction between HCl and gold. Gold does not readily react with acids or other chemicals and remains largely inert, which is why it is commonly used in jewelry and other decorative items. Therefore, there is no reaction between hydrochloric acid and gold
Explain the apparent unreactivity of aluminium in
terms of its oxide layer
Aluminium (Al) is a reactive metal, but it appears unreactive due to the presence of a thin layer of oxide that forms on its surface when it comes into contact with air. This oxide layer is composed of aluminium oxide (Al2O3) and is very stable and resistant to further oxidation. The oxide layer acts as a protective layer, preventing further oxidation of the metal.
When aluminium is exposed to air, the surface layer reacts with oxygen to form a layer of aluminium oxide. This layer is typically only a few nanometers thick, but it is very dense and adheres strongly to the metal surface. The oxide layer effectively seals the underlying metal from further exposure to the environment, preventing corrosion and other forms of chemical attack.
In the presence of an acid or base, the oxide layer is dissolved, exposing the underlying metal to further reaction. This is why aluminium can react with acids and bases, despite its apparent unreactivity in air. However, once the acid or base is removed, the oxide layer reforms, restoring the protective barrier and preventing further reaction.
In summary, the apparent unreactivity of aluminium is due to the presence of a stable and protective oxide layer on its surface that prevents further oxidation and chemical attack.
State the conditions required for the rusting of
iron and steel to form hydrated iron(III) oxide
Water: Rusting requires the presence of water or moisture. This is because water is needed to react with iron to form hydrated iron(III) oxide.
Oxygen: Rusting also requires the presence of oxygen. Iron reacts with oxygen in the presence of water to form hydrated iron(III) oxide.
Electrolytes: Rusting is accelerated in the presence of electrolytes, such as salts and acids. This is because these substances increase the conductivity of the water, allowing for faster and more efficient transfer of electrons between the iron and oxygen.
In the absence of any one of these conditions, rusting will not occur. For example, in a dry environment, rusting cannot occur because there is no water to react with the iron. Similarly, in the absence of oxygen, rusting cannot occur because iron cannot react with water to form hydrated iron(III) oxide.
State some common barrier methods
painting, greasing and coating with plastic
Describe how barrier methods prevent rusting by
excluding oxygen or water
in absence of oxygen or water, rusting can’t happen as it can’t react with water to form hydrated iron(III) oxide
Painting: Painting is a common barrier method used to prevent rusting. A layer of paint is applied to the surface of the metal, creating a barrier that prevents oxygen and water from coming into contact with the metal.
Coating: Coating is similar to painting, but uses a different material, such as a plastic or polymer, to create a barrier. This method is commonly used in the automotive industry to protect car bodies from rusting.
Greasing: Greasing involves applying a layer of grease or oil to the metal surface, which prevents water from coming into contact with the metal. This method is commonly used to protect metal components in machinery and engines.
Galvanizing: Galvanizing involves coating the metal surface with a layer of zinc, which is more reactive than iron and will corrode in preference to the iron. This method is commonly used to protect steel structures, such as bridges and buildings.
Describe the use of zinc in galvanising as an
example of a barrier method and sacrificial
protection
Galvanizing is a process that involves coating iron or steel with a layer of zinc, either by hot-dip galvanizing or electroplating. Zinc is commonly used for galvanizing because it is highly reactive and readily corrodes in preference to iron. This makes it an effective sacrificial anode, which provides protection to the underlying iron or steel.
In the galvanizing process, the iron or steel is first cleaned to remove any impurities or surface contaminants. The cleaned surface is then dipped into a bath of molten zinc, which adheres to the surface of the metal, forming a protective layer. Alternatively, the metal can be electroplated with a layer of zinc using an electric current.
The zinc layer acts as a barrier, preventing water and oxygen from coming into contact with the underlying metal surface. In addition, because zinc is more reactive than iron, it will corrode preferentially to the iron, sacrificing itself to protect the underlying metal from corrosion. This process is known as sacrificial protection.
Over time, the zinc layer will gradually corrode and eventually wear away. However, by the time the zinc layer is completely consumed, the underlying metal will have been protected from corrosion for a significant period of time. The effectiveness of the sacrificial protection depends on the thickness of the zinc layer and the environment in which the metal is exposed.
Galvanizing is commonly used to protect steel structures, such as bridges, buildings, and pipelines, from corrosion. It is also used in the manufacturing of many everyday products, such as automotive parts, household appliances, and fencing.
Explain sacrificial protection in terms of the
reactivity series and in terms of electron loss
Sacrificial protection is a method of protecting a metal from corrosion by connecting it to another more reactive metal. The principle of sacrificial protection is based on the reactivity series of metals, which is a list of metals arranged in order of their reactivity towards oxygen and water.
In the reactivity series, metals at the top of the list, such as potassium and sodium, are highly reactive and readily lose electrons to form positive ions. Metals at the bottom of the list, such as gold and platinum, are relatively unreactive and do not readily lose electrons.
When two different metals are connected in an electrolyte, such as saltwater, the more reactive metal will tend to lose electrons and undergo oxidation, while the less reactive metal will tend to gain electrons and undergo reduction. This creates a flow of electrons from the more reactive metal to the less reactive metal, known as a galvanic cell.
In sacrificial protection, a more reactive metal, such as zinc or magnesium, is connected to the metal to be protected, such as iron or steel. The more reactive metal acts as a sacrificial anode, which corrodes preferentially to the less reactive metal, providing protection against corrosion.
In terms of electron loss, sacrificial protection involves the transfer of electrons from the more reactive metal to the less reactive metal, which results in the less reactive metal being protected from corrosion. The more reactive metal loses electrons and undergoes oxidation, while the less reactive metal gains electrons and undergoes reduction. This process is driven by the tendency of the more reactive metal to lose electrons and form positive ions, which are then attracted to the less reactive metal.
Describe the ease in obtaining metals from their
ores, related to the position of the metal in the
reactivity series
the more up the metal the harder as its more reactive and can more easily chemically combine with other elements making it hard to extract
the lower(less reactive) the easier to extract as they don’t easily react w other elements
what is the main ore of aluminium
bauxite
how is aluminium extracted
electrolysis
from which ore is iron extracted from?
hematite
how is iron extracted by hematite
in a blast furnace
Describe the extraction of iron from hematite in
the blast furnace
(a) Burning of carbon (coke) to provide heat and produce carbon dioxide:
Coke is burned in the blast furnace to provide the heat required for the extraction of iron. The carbon in the coke reacts with the oxygen in the air to produce carbon dioxide and heat.
(b) Reduction of carbon dioxide to carbon monoxide:
Carbon dioxide produced from the combustion of coke is reduced to carbon monoxide by passing it through hot coke.
(c) Reduction of iron(III) oxide by carbon monoxide:
The carbon monoxide produced in step (b) is then used to reduce the iron(III) oxide in the hematite ore to iron metal. The reaction can be represented by the following equation:
Fe2O3 + 3CO → 2Fe + 3CO2
(d) Thermal decomposition of calcium carbonate/limestone to produce calcium oxide:
Limestone (calcium carbonate) is added to the furnace to help remove impurities in the ore. When heated, it decomposes to produce calcium oxide and carbon dioxide.
CaCO3 → CaO + CO2
(e) Formation of slag:
The impurities in the ore react with the calcium oxide to form a molten slag, which is less dense than the molten iron and floats on top of it. The slag is then removed from the furnace.
Overall, the extraction of iron from hematite ore in the blast furnace involves the burning of coke to provide heat and produce carbon dioxide, reduction of carbon dioxide to carbon monoxide, reduction of iron(III) oxide by carbon monoxide, thermal decomposition of calcium carbonate/limestone to produce calcium oxide, and the formation of slag.
State the symbol equations for the extraction of
iron from hematite
(a) C + O2 → CO2
(b) C + CO2 → 2CO
(c) Fe2O3 + 3CO → 2Fe + 3CO2
(d) CaCO3 → CaO + CO2
(e) CaO + SiO2 → CaSiO3
which ore do we extract aluminium from?
purified bauxite / aluminium oxide
Describe the extraction of aluminium from
purified bauxite / aluminium oxide
The extraction of aluminum from purified bauxite or aluminum oxide is done through the process of electrolysis. Here are the steps involved in the extraction process:
Preparation of alumina: Bauxite ore is purified to yield a white powder, aluminum oxide, also known as alumina. This is done by crushing the bauxite ore, mixing it with sodium hydroxide, and heating it in a kiln to produce pure alumina.
Preparation of cryolite: The pure alumina is then mixed with cryolite, a mineral that acts as a solvent for alumina and lowers its melting point.
Electrolysis: The alumina-cryolite mixture is then dissolved in a large electrolytic cell, which is made of steel and lined with carbon. Carbon anodes are immersed in the electrolyte, and a large graphite cathode is suspended in the center of the cell.
Electrical current: A direct current is passed through the cell, causing the alumina to break down into aluminum ions and oxygen ions. The aluminum ions are attracted to the cathode, where they gain electrons and form molten aluminum metal. The oxygen ions react with the carbon anodes to form carbon dioxide gas.
Collection of aluminum: The molten aluminum is then siphoned off and transferred to holding tanks, where it solidifies into aluminum ingots.
Recycling: The remaining electrolyte, which contains dissolved alumina and cryolite, is pumped out of the cell and recycled for use in the next batch of alumina.
Overall, the extraction of aluminum from purified bauxite or aluminum oxide involves a complex process of electrolysis, which requires a large amount of electrical energy and specialized equipment. However, this process is essential for the production of aluminum, which is a versatile and important metal used in a wide range of applications, from aircraft manufacturing to packaging materials.
state the metals that can react with cold water starting from the most reactive
Potassium
Sodium
Calcium
Magnesium
Note that metals such as zinc, iron, copper, and silver are not reactive enough to react with cold water.
state the metals that can react with steam starting from the most reactive
Potassium
Sodium
Calcium
Magnesium
Aluminum
Zinc
Iron
Note that metals such as copper and silver do not react with steam.
state the metals that react with dilute hydrochloric acid
Magnesium
Zinc
Iron
Tin
Lead
Nickel
Copper and silver do not react with dilute hydrochloric acid.
Note that the reaction of these metals with hydrochloric acid produces hydrogen gas and the corresponding metal chloride.
what is the role of cryolite in the extraction of aluminium from bauxite?
to reduce the operating temperature of aluminium oxide so that the extraction of it is much cheaper
why the carbon anodes need to be regularly
replaced in the extraction of aluminium?
so that we can extract pure aluminium as the carbon anode reacts with oxygen in the air to form CO2
what are the half equations of the extraction of aluminium?
Al 3+ 3e—-> Al
2O2- → O2 + 4e-
Where are metals found in the periodic table?
metals are found on the left of the table- to the left of the ladder which starts above aluminium and steps down to the right
List five properties of metals
conducts electricity and heat
shiny
malleable
ductile
some are magnetic
Which group is called the alkaline metals?
Group 1
Li
Na
K
Rb
What group is called the Alkaline Earth Metals?
Group 2
Be
Mg
Ca
Sr
What is special about the transistion metals?
They form colourful compounds
&
They often have more than one valency
Fe 2+ and Fe 3+
What group are called the Halogens?
Group 7
F
Cl
Br
I
They are all diatomic!
What group is called the noble gases?
Group 0
He
Ne
Ar
Kr
they all have a full outer shell and are inert (unreactive)
Name the four metals less reactive than hydrogen in the reactivity series
Hydrogen
Copper
Silver
Platinum
Gold- unreactive
Name the five metals more reactive than carbon in the reactivity series
potassium
sodiium
calcium
magnesium
aluminium
carbon
All these metals must be extracted using electrolysis as carbon cannot displace them as it is less reactive
Name the four metals between carbon and hydrogen in the reactivty series
Carbon
Zinc
Iron
Tin
:Lead
Hydrogen
These metals can be extracted from their ores using carbon or coke in a blast furnace
Why can iron be reduced or extracted from its metal ore using coke (carbon)?
Carbon is more reactive than iron
Carbon displaces iron
iron is reduced
Henry threw some copper into some hydrochloric acid. He expected to see a reaction, some fizzing, but nothing happened. explain why?
copper is less reactive than hydrogen
copper cannot displace hydrogen and so it does not react
Henry threw some copper into some hydrochloric acid. He expected to see a reaction, some fizzing, but nothing happened. explain why?
copper is less reactive than hydrogen
copper cannot displace hydrogen and so it does not react
Describe three properties of the group 1 metal sodium
soft - can be cut with a knife
shiny when cut but then quickly reacts and becomes dull
low melting point
Finish the general equation
reactive metal + water –>
remember the fizzing?
reactive metal + water –> metal hydroxide + hydrogen
What is the chemical reaction between lithium and water?
Li (s) + H2O(l) –> LiOH(aq) + H2(g)
Lithium hydroxide is an alkali- it will turn universal indicator blue
What would you observe if you put some sodium in water?
How would this compare to potassium in water?
For sodium
fizzing, moving around on the surface of the water
melts into a ball, metal disappears
For potassium - it is more reactive
more vigorousfizzing
moving around on the surface of the water more quickly
melts into a ball and bursts into flame (lilac in colour)
metal disappears more rapidly
What is the chemical reaction between sodium and water?
Na (s) + H2O(l) –> NaOH(aq) + H2(g)
sodium hydroxide is an alkali- it will turn universal indicator blue
What is the chemical reaction between potassium and water?
K (s) + H2O(l) –> KOH(aq) + H2(g)
potassium hydroxide is an alkali- it will turn universal indicator blue
How would the reaction differ between potassium and rubidium?
Potassium
lilac flame
Rubidium
explosive
What is an alloy?
A mixture of a metal and metal or a metal and non-metal which changes both the physical and chamical properties
Give three examples of an alloy
Brass- copper + zinc
Bronze- copper + tin
Steel- iron + carbon
How does the introduction of a different sized atom to a pure metal change its physical properties?
The smaller atoms disrupts the arrangment of the metal ions,
They no longer arrange themselves in neat rows
They do not have layers which can slide over one another
They are no longer malleable- they are harder and stronger
When calcium reacts with hydorchloric acid, hydrogen forms.
How can the hydrogen be collected?
hydrogen can be collected by downward displacement of water
OR
downward displacement of air - upside down test tube- hydrogen is less dense than air and will rise into the test tube and push the air downward
What are the products in this reaction?
Mg + H2O (g) –>
steam
Mg + H2O (g) –> MgO + H2
steam
with steam the oxide is formed-not the hydroxide!
Both potassium and sodium are found in group 1
Why is potassium more reactive than sodium?
potassium atom is larger
outer electrons of potassium are further from the nucleus
less electrostatic attraction between the negative outer electrons and positive nucleus
easier to remove the outer electron from potassium
Also, there are more shells between the nucleus and outer electrons in potassium
the electrons in these shells repel the outer electrons and is called electron shielding
easier to remove the outer electron from potassium
potassium is more reactive for these two reasons!
Complete the reaction
Al + Fe2O3 –>
Thermite reaction!!
Is aluminium more reactive than iron? YES!
2Al + Fe2O3 –> Al2O3 + 2Fe
Aluminiuim is more reactive than iron
aluminium displaces the iron
This is a displacement reaction
Complete this general reaction
metal + steam –>
Metal + steam –> metal oxide + hydrogen
You still get hydrogen but now you have the oxide- not the hydroxide
What is the test for hydrogen gas?
Flaming splint
you hear a squeaky pop!
Why does it take time for aluminium to start reacting with an acid?
aluminium forms an impermeable aluminium oxide layer.
The acid must get through that layer before it comes into contact with the pure metal.
This impermeable oxide layer on aluminium is an advantage- iron reacts with oxygen and rusts entirely through the metal but aluminium forms an impermeable oxide layer protecting the pure aluminium below.
Complete the general word equation
more reactive metal + less reactive metal compound –>
more reactive metal + less reactive metal compound –>
more reactive metal compound + less reactive metal
the more reactive metal displaces the less reactive metal
This is a displacement reaction
Complete the displacement reaction and describe what you would observe
Zn + CuSO4 –>
Is zinc more reactive than copper?
Yes
Zn + CuSO4 –> ZnSO4 + Cu
greysolid & blue solution –> colourless solution & orange/pink soild
Below is the thermite reaction!!
2Al + Fe2O3 –> Al2O3 + 2Fe
Where is this used and is the reaction an exothermic or endothermic reaction? How do you know?
Thermite reaction is used to connect (fuse) iron rails together on a railway.
This reaction is carried out above the seam between the two rails
The reaction is exothermic- it releases heat rapidly and exceed the melting point of iron which melts out the bottom of the vessel and onto the seam.
Complete the displacement reaction and describe what you would observe
Fe + ZnSO4 –>
Is iron more reactive than zinc?
No- the rion cannot displace the zinc
No reaction - grey metal in colourless solution with no change to appearance
Complete the metal displacement reaction
Ca + MgNO3 –>
Ca + 2MgNO3 –> Ca(NO3 )2 + 2Mg
Which reaction will be more vigorous and why?
Mg + Fe2O3 –>
Zn + Fe2O3 –>
The Mg and Fe reaction will be more vigorous because Mg and Fe are further apart in the reactivity series.
The further apart metals are in the reactivity series the more violent their displacement reactions will be.
How can you use metal and acid reactions to order metals in terms of reactivity?
Place the metals in the same concentration and type of acid and compare the rate of fizzing
the more vigorous the fizzing, the more reactive the metal
Define a metallic bond
the electrostatic attractionn between potive metal ions and the negative delocalised electrons
Describe the structure of a metal
regular arrangement of metal ions
layers of metal ions surrounded by a sea of delocalised electrons
Why do metals have high melting points?
many strong metallic bonds in a giant structure
requires a lot of energy to overcome
Are metals soluble in water or organic solvents?
No- they are not soluble in either.
NOTE: reactive metals react with water but they are not soluble
Why do metals conduct electricity?
metals have delocalised electrons which are free to move
and carry charge
Why are metals malleable?
metal ion layers can slide over one another
without distrubing the metallic bonds
Which four materials are added to a blast furnace?
iron (III) oxide
limestone
coke
hot air
What are the products from a blast furnace?
iron metal
carbon dioxide
slag
Which product in a blast furnace causes a concern from the environment?
carbon dioxide
is a greenhouse gas which may lead to global warming
Which reaction gets everything hot in the blast furnace?
combustion of coke
C + O2 –> CO2 exothermic!!!
Which reaction forms the reducing agent in the blast furnace?
C + CO2 –> 2CO
coke is added in excess so that CO is formed (carbon monoxide)
carbon monoxide is the reducing agent- it reduces the iron (III) oxide
What is the formula for haematite?
iron (III) oxide
What is the name of iron ore?
Hematite
Complete the redox reaction which happens in the blast furnace
Fe2O3 + 3CO –>
Fe2O3 + 3CO –> 3CO2 + 2Fe
Fe has been reduced - lost oxygen
C is oxidised - gained oxygen
Explain how the reaction below is a redox reaction- a reaction where both oxidation and reduction occurs
Fe2O3 + 3CO –> 3CO2 + 2Fe
Fe2O3 + 3CO –> 3CO2 + 2Fe
Fe has been reduced - lost oxygen
C is oxidised - gained oxygen
Which mnemonic is used to work out which elements are reduced or oxidised in a reacion?
OIL RIG
OIL - oxidation is loss of electrons
RIG - reduction is gain of electrons
REMEMBER: if the atom has gained or lost oxygen you must speak about that and not the gain or loss of electrons
Why do we add limestone to a blast furnace?
To get rid of the impurity found in iron ore
First- the limestone thermally decomposes to calcium oxide because the blast furnace is hot
CaCO3 –> CaO + CO2
The calcium oxide then reacts with the impurity silicon dioxide to form calcium silicate OR SLAG
CaO + SiO2 –> CaSiO3
SLAG
The slag is less dense than the molten iron and float on top
Complete the thermal decomposition of calcium carbonate in a blast furnace
CaCO3 –>
Thermal decomposition means that the compound breaks apart by heating
CaCO3 –> CaO + CO2
Complete the reaction which forms SLAG in a blast furnace
CaO + SiO2 –>
This is a neutralisation reaction
metal oxide CaO - acidic
non-metal oxide SiO2 - alkaline
CaO + SiO2 –> CaSiO3
alkaline + acid –> salt
What is the name of the impurity in hematite?
silicon dioxide
SiO2
What is the chemical formula for SLAG which forms in a blast furnace/
CaSiO3
Why is it easy to separate SLAG from iron metal in a blast furnace?
Both are molten (melted) but the slag is less dense and floats on top of the molten iron
What type of reaction is this?
C + O2 –> CO2
combustion or oxidation as carbon gained oxygen
What type of reaction is this?
CaCO3 –> CaO + CO2
Thermal Decomposition
the CaCO3 is decomposing or breaking apart
What is the reaction for rusting of iron?
4Fe + 3O2 + 5H2O –> 2Fe2O3*5H2O
iron needs both water and oxygen to rust!
Note: salt in not needed but is a catalyst- it speeds up the reaction by lowering hte activation energy but is not used in the reaction
What is the chemical formula for rust?
Fe2O3
What is the chemical name for rust?
iron (III) oxide
Name three barrier methods to stop iron from rusting
paint - to stop oxygen and water getting to iron
coat in plastic- to stop oxygen and water getting to iron
oil or grease- to stop oxygen and water from getting to irion
Name two sacrificial methods to stop iron from rusting
galvanising- coating in zinc- used for buckets etc
sacrificial protection with block of magnesium or zinc- used for bridges or large structures where coating in zinc is too expensive
What is the name of this this protection method for iron?
Fe2O3 + 3Zn –> 3ZnO + 2Fe
sacrificial protection
Zn metal –> Zn 2+ + 2e-
zinc reacts and gives 2 electrons to any iron ions which have formed to reduce it back to iron metal- protecting the iron and sacrificing the zinc
Fe 3+ + 3 e- –> Fe metal
Which metal is being reduced and which one is being oxidised? How do you know?
Fe2O3 + 3Zn –> 3ZnO + 2Fe
Fe2O3 + 3Zn –> 3ZnO + 2Fe
iron is reduced as it is losing oxygen
zinc is oxidised as it is gaining oxygen
Metal carbonates thermally decompose to form a metal oxide and carbon dioxide
Which properties of carbon dioxide prevents us from collecting it by downward displacement of water and allows us to collect it by downward displacement of air?
carbon dioxide is soluble in water- if collected by downward dislacement of water the carbon dioxide would dissolve in the water
carbon dioxide is more dense than air- if a tube was placed in a upright test tube the more dense carbon dioxide would fill the test tube and push the air out.
What is the test for carbon dioxide?
bubble though limewater
limewater turns cloudy
What would you observe in this thermal decomposition reaction?
CuCO3 –> CuO + CO2
green black
green power moves as gas escapes the green powder turns black
Write the thermal decomposition reaction of Copper (II)carbonate
CuCO3 –> CuO + CO2
Complete the reaction for the thermal decomposition of calcium carbonate
CaCO3 –> CaO + CO2
Why can’t we extract aluminium from aluminium ore using coke (carbon)
Carbon is less reactive than Aluminium
it cannot displace aluminium from aluminium ore?
What is the name of aluminium ore?
Bauxite
Al2O3
What method do we use for the extraction of aluminium form aluminium ore?
electrolysis
Define electrolysis
The decomposition of a compound using electricity
Why do we need to melt the aluminium ore before carying our electrolysis?
Aluminium ore is ionic, when melted the metal ions are free to move and carry charge
we need electricity to pass through the molten ore for electrolysis to occur
What is added to aluminium oxide to make the extraction of aluminium cheaper?
Cryolite is added to the aluminium ore- this reduced the melting point of the ore
Less heat is used- cheaper process
Why is electrolysis more expensive than using a blast furnace to extract a metal from its metal ore?
Electrolysis used both electricity and heat to extract the metal.
Blast furnace only needs heat
Which ions are free to move when Al2O3 is melted during electrolysis
Al 3+
O 2-
When aluminium ore is molten the two ions which are mobile are
Al 3+
O 2-
Which ion will move toward the cathode? The negative electrode?
Which ion eill move towards the anode? the positive electrode?
Al 3+ is positively charged and will be attracted to the cathode or negatively charge electrode
O 2- is negatively charged and will be attracted to the anode or positviely charge electrode
Why is the entire container charge negatively in the electrolysis of aluminium ore?
The positive aluminium ions will be attracted to the bottom of the container allowing the aluminium to form there- it can then be tapped off
Why does aluminium oxide conduct when molten (melted) but not when it is a solid?
Aluminium oxide is ionic, when molten the ions are free to move and carry charge
When in the solid form the ions are not free to move and cannot carry charge
Give two properties of carbon dioxide
It is soluble in water to form an acid
It is more dense than air
Use the image below to explain why alloys are less malleable than pure metals
A pure metal will have a regular arrangement of atoms. The rows of metal atoms can slide easily over one another without disrupting the metallic bond
Alloys are a mixture of metals or a metal and non-metal. This often disrupts the regular arrangement. There are no complete rows of atoms which can slide over each other. Not malleable-harder substance
Name and formula of the common iron ore?
Hematite (mostly Fe2O3 + some impurities)
Steps of iron extraction + the equations not including the purification steps (3)
Coke(carbon) is burnt to give off heat
C + O2 –> CO2
Carbon monoxide is made
C + CO2 –> 2CO
Iron(III) oxide is reduced
Fe2O3 + 3CO –> 2Fe + 3CO2
Steps and equations to the purification steps (2)
1.Break down limestone in the furnace
CaCO3 –> CaO + CO2
2.CaO (lime) reacts with the sand that’s made of mainly silicon dioxide to make slag (calcium silicate)
CaCO3 + SiO2 –> CaSiO3
Role of CaCO3?
Removes impurities
Name, Chemical name and formula of the impurity formed.
How is it tapped off?
Slag is known as Calcium silicate (CaSiO3)
It’s less dense than molten iron so it floats on top of the molten iron and is then tapped off.
Name the reducing agent?
Carbon monoxide (CO)
Name of the zinc ore? What compound does it contain most of?
Name: Zinc blende
It’s mainly zinc sulfide
Steps of zinc extraction + the equations
Roast the zinc blende
2ZnS + 3CO2 –> 2ZnO + 2SO2
OXIDE CAN BE REDUCED BY 2 WAYS
A = Using CO (approx 907 degrees C):
ZnO + CO –> Zn + CO2
B = Electrolysis:
Zinc is deposited at the cathode.
Zn2+(aq) + 2e- –> Zn(s)
Carbon monoxide role?
Reducing agent
Why use electrolysis to extract zinc?
The zinc extracted by electrolysis is at very high purity where as with using CO the zinc is not pure and you’ll need to take further steps to remove the impurities.
Half ionic equations at the anode and at the cathode.
What else is produced at the anode? Why?
CATHODE:
Al3+ + 3e- –> Al
ANODE:
2O2- -4e- –> O2
Forms Carbon dioxide as some of the oxygen reacts with the carbon from the graphite electrodes.
C + O2 –> CO2
Melting point of Alumina (Al2O3)
2045 degrees C
What is the electrolyte made up of
Al2O3 dissolved in Cryolite. There are also the impurities
Reason for using Cryolite
It lowers the temperature that needs to be maintained for electrolysis from 2045 to around 945 degrees C
Uses of Aluminium? (3)
Form alloys
Car frames and parts
Bike frames
Where do we find most metals?
In the earth’s crust
What is the crust mainly made up of?
Compounds, some elements such as:
Cu, Ag, Hg, Pt, Au - occur native
45% O2
27% silicon
What is the crust mainly made up of?
Compounds, some elements such as:
Cu, Ag, Hg, Pt, Au - occur native
45% O2
27% silicon
Why do some elements occur native in the crust?
They’re uncombined because they are “unreactive”
What are the two main non-metal elements in the crust?
What compounds do they occur in?
Si and O - make up nearly 3/4
occur together in compounds e.g silicon dioxide (silica or sand)
O2 found in compounds such as iron(III) oxide, aluminium oxide, calcium carbonate
What percentage of the earth’s crust is metal?
2%
What metals are classified as “precious metals” and why?
Gold, silver, platinum and palladium
- scarce, expensive, often kept as a store of wealth
Definition of ore
a rock from which metals are obtained / extracted
What ore is sodium chloride found in?
rock salt
What ore is aluminium oxide found in? What other elements are in this ore?
bauxite
- contains impurities such as sand and iron oxide
6 questions mining companies must consider before digging up ore?
how much ore is there
how much metal will we get from it
are there any special problems getting the ore out
how much will it cost to mine the ore and extract the metal from it
how much will we be able to sell the metal for
will they make profit
what do the costs of mining consist of? 8
roads, buildings, mining equipment, the extraction plant, transport, fuel, chemicals and wages
Can the prices of an ore change?
Yes - even low-quality / low-grade ore may be valuable one year
why may local people object to mining operations?
What are the pros?
may spoil an area
air and rivers can become polluted
P - may welcome new jobs
How would you extract metals such as gold, silver or platinum from the earth?
They are native - occur in their ore as elements
All you need to do is separate the metal from sand and other impurities
DOES NOT INVOLVE CHEMICAL REACTIONS
What does extract mean?
To remove a metal from its ore
How are metals less reactive than carbon extracted?
They’re heated with carbon (or CO) or a suitable reducing agent so that they’re reduced
They’re less stable
How are metals more reactive than carbon extracted?
Their compounds are very stable
need electrolysis to reduce them
costs a lot because it uses electricity
In what form is carbon used during extraction?
in the form of coke (coal)
What 3 metals are below C in the reactivity series?
Zn, Fe, Pb
What 5 metals are above C in the reactivity series?
K, Na, Ca, Mg, Al
What form is the metal in when its added to carbon in a furnace?
In its metal oxide
What does the actual reducing during the process using carbon for extraction?
If carbon reacts with the limited amount of oxygen, this may bring about the actual reduction
Give the basic chemical equation for the extraction of iron ore
Fe2O3 + 3CO —> 2Fe + 3CO2
iron (III) oxide
Give the basic chemical equation for the extraction of aluminium ore
(extracted by electroysis)
2Al2O3 —> 4Al + 3O2
What does zinc blende consist of?
Mainly zinc sulfide - ZnS
What is the first step in extracting zinc from zinc blended?
Give the equation
First, zinc blende is roasted in air giving zinc oxide and sulfur dioxide.
2ZnS + 3O2 —> 2ZnO + SO2
In which two ways can zinc oxide be turned into zinc
- Using carbon monoxide
- By electrolysis
Explain how zinc is extracted from zinc oxide by using carbon monoxide
ZnO + CO —> Zn + CO2
What does the final mixture contain? How is zinc extracted from this? (zinc extraction using CO)
Zinc and a slag of impurities
Separated by fractional distillation (907 degrees C)
What is zinc oxide dissolved in so it can be extracted by electrolysis? Why?
Dissolved in dilute sulfuric acid (sulfur dioxide made during roasting stage)
To reduce its melting point (1975 degrees C) (its also insoluble in water)
What is formed when the zinc oxide is dissolved in dilute sulfuric acid? Why?
Zinc sulfate - zinc oxide is a base so it neutralises the sulfuric acid giving a solution of zinc sulfate
What is the result fo the electrolysis of zinc sulfate?
half equation
Zinc is deposited at the cathode
Zn2+ + 2e- —> Zn (reduction)
Why is the method of electrolysis most commonly used to extract zinc?
gives zinc of a very high purity
What other metals are found in zinc blende and what happens to them?
calcium and lead appear as impurities in the zinc blende and these metals are recovered and sold too
What happens to the zinc deposited onto the cathode?
Scraped off the cathode and melted into bars to sell
4 uses of Al
overhead electricity cables (with a steel core for strength)
cooking foil and food cartons
drinks cans
coating CDs and DVDS
3 reasons why Al is used for overhead electricity cables
a good conductor of electricity (not as good as copper, but cheaper and much lighter);
ductile,
resists corrosion
3 reasons why Al is used for cooking foil and food cartons
non-toxic,
resistant to corrosion,
can be rolled into thin sheets
3 reasons why Al is used tor drink cans
light,
non-toxic,
resistant to corrosion
2 reasons why Al is used for coating CDs and DVDS
can be deposited as a thin film;
shiny surface reflects laser beam
2 uses of Cu
electrical wiring
saucepans and saucepan bases
2 reasons why Cu is used for electrical wiring
one of the best conductors of electricity,
ductile
4 reasons why Cu is used for saucepans and saucepan bases
malleable,
conducts heat well, unreactive,
tough
3 uses of zinc
protecting steel from rusting
coating or galvanising iron and steel
for torch batteries
Reason why Zn is used for protecting steel from rusting
offers sacrificial protection to the iron in steel
2 reasons why Zn is used for coating or galvanising iron and steel
resists corrosion, but offers sacrificial protection if coating cracks
2 reasons why Zn is used for torch batteries
gives a current when connected to a carbon pole, packed into a paste of electrolyte
Definition of alloy
A mixture where at least one other substance is added to a metal, to improve its properties; the other substance is often a metal too
Why do metals have to be molten to make an alloy?
So that the atoms of the second metal can entre the lattice
Why is an alloy better than just a pure metal?
Turning a metal into an alloy changes its properties and makes it more useful.
Why is an alloy stronger than a pure metal?
Metal atoms are arranged in a lattice (in a pure metal)
When pressure is applied, e.g hammering, the layers can slide over each other easily
When the metal is turned into an alloy, new atoms of different sizes enter the lattice. The layer can NO LONGER slide easily
What is another property besides strength which might change in an alloy?
Could be more resistant to corrosion
Name 2 alloys
Brass and Aluminum alloy 7075 TF
What is brass made from?
70% Copper
30% Zinc
What are the special properties of brass?
Harder than copper
Does not corrode
What are the 3 uses of brass?
Musical instruments
Ornaments
Doorknobs
What is aluminium alloy made from?
90.25 % Aluminium
6% Zinc
2.5% Magnesium
1.25% Copper
What are the special properties of Al alloy?
light but very strong
does not corrode
What is the use of Al alloy?
aircraft
Why is pure iron not good for building things?
too soft
stretches quite easily
rusts very easily
What does mild steel contain?
99.7% iron 0.3% carbon
What is mild steel used for and why is it good for these things?
Hard and Strong
buildings
ships
car bodies
machinery
What does stainless steel contain?
20% chromium, 10% nickel and 70% iron
What is stainless steel used for and why is it good for these things?
Hard and Rustproof
cutlery
equipment in chemical factories
surgical tools (easy to sterilise)
Basic summary of what goes on in a blast furnace
A mixture called the charge, containing iron ore is added through the top of the furnace.
Hot air is blasted in through the bottom.
After a series of reactions, liquid iron collects at the bottom of the furnace.
What 3 things are in the charge?
Iron ore
Limestone (CaCO3 - calcium carbonate)
Coke (made from coal - almost pure carbon)
What are the 3 main reactions that occur in a blast furnace?
Coke burns, giving off heat
Carbon monoxide is made
Iron (III) oxide is reduced
Give the chemical equation for stage 1 - coke burning with an explanation of what’s happening
The blast of air starts the coke burning - reacts with oxygen in the air to give carbon dioxide
C + O2 —> CO2
Is stage 1 a redox reaction? How?
yes
- C is oxidised to carbon dioxide
Where is the oxygen which reacts with C from? (stage 1)
The blast of hot air
What’s special about the reaction between C and O2?
It’s EXOTHERMIC - gives off heat, which helps to heat the furnace
Give the chemical equation for stage 2 - CO is made with an explanation of what’s happening
Carbon dioxide reacts with more coke:
C + CO2 —> 2CO
Is stage 2 a redox reaction? How?
Yes
- CO2 loses oxygen and is reduced
How does stage 2 reaction differ from stage 1?
It’s ENDOTHERMIC - takes in heat from the furnace
- good as stage 3 needs a lower temperature
Give the chemical equation for stage 3 - reduction of iron oxide with an explanation of what’s happening
where extraction occurs
CO reacts with iron ore to give liquid iron
this trickles to the bottom of the furnace
Fe2O3 + 3CO —> 2Fe 3CO2
What is special about carbon monoxide in the blast furnace?
Acts as a REDUCING AGENT
reduces iron (III) oxide to the metal
CO oxidised to CO2
What is the limestone for?
To remove impurities
- Give the chemical equation for limestone in a blast furnace - with an explanation of what’s happening + purpose
Limestone thermally decomposes in the heat
CaCO3 —> CaO + CO2
- to produce CaO which will remove sand that was present in the ore
- Give the chemical equation for calcium oxide in a blast furnace - with an explanation of what’s happening
Calcium oxide reacts with the sand, which is mainly silicon dioxide/silica.
CaO + SiO2 —> CaSiO3
calcium + silica + calcium silicate
oxide
What happens to calcium silicate in a blast furnace?
Forms a slag which runs down the furnace and floats on the iron
What type of reaction is the reaction between CaO and SiO2
CaO - basic oxide SiO2 - acidic oxide CaSiO3 - salt
NEUTRALISATION
What is done with the slag from the blast furnace?
Molten slag is drained off
When it solidifies, it is sold, mostly for road building
What 2 waste gases are produced by the blast furnace? What are they used for?
Why are they waste gases?
carbon dioxide and nitrogen (come out the top of the furnace)
Heat is transferred from them to heat the incoming blast of air
Have not reacted with anything CO2 - stage 3 N - air
What is the iron from a blast furnace called?
Pig iron
Is iron from a blast furnace pure? Why?
NO
carbon and sand are the main impurities
phosphorus and sulfur compounds are also present from the iron ore
What is the pig iron used for?
Some is run into moulds to make cast iron
Most made into steels
What is cast iron used for and why?
Used for things like canisters for bottled gas and drain covers
- hard but brittle due to its high carbon content
What do scientists do to the rocks surrounding the area (where they want to mine) and why?
They test rocks and analyse the results in order to find out how much bauxite there is.
If the tests are satisfactory, mining begins.
What colour is bauxite?
Red-brown
Is it easy to mine bauxite? Why?
Yes - found near the surface so it’s easy to dig up
Where is the ore of Al taken to and what is it processed to?
Taken to a bauxite plant, where impurities are removed.
The result is white aluminium oxide or alumina.
Where is the aluminium oxide taken to be processed?
Alumina is taken to another plant for electrolysis. May even be sent yo another country where electricity is cheaper.
What happens to the extracted aluminium?
Made into sheets and blocks and sold to other industries.
Describe the basic structure of where Al2O3 is electrolysed
Electrolysis carried out in large steel tank
lined with carbon which acts as a cathode (-)
big blocks of carbon hang in the middle of the tank and act as the anode (+)
What is aluminium oxide dissolved in for the process of electrolysis and why?
Dissolved in molten cryolite.
alumina melts at 2045 degrees C
impossible to keep the tank that hot
dissolved to decrease melting point as cryolite has lower mp
What is cryolite also called?
sodium aluminium fluoride
Give the half equation for the cathode and a brief explanation (Al extraction)
At cathode - reduction - Al ions gain electrons
Al3+ + 3e- –> Al
What happens to the aluminium when it is reduced?
Drops to the bottom of the cell as molten metal. This is run off at intervals.
What happens to the molten aluminium? (AL extraction)
Some will be mixed with other metals to make alloys.
Some is run into moulds, to harden into blocks.
Give the half equation for the anode and a brief explanation (Al extraction)
At anode - oxidation - oxygen ions lose electrons
2O2- —> O2 + 4e-
Why do the carbon anodes need to be replaced? Give a chemical equation (Al extraction)
Oxygen gas bubbles off and reacts with the anode
C + O2 —> CO2
Carbon block gets eaten away and needs to be replaced
What is the overall reaction for the electrolysis of alumina?
Alumina is broken down giving aluminium
2Al2O3 —> 4Al + 3O2
7 properties of aluminium
bluish-silver shiny metal
Has a low density
good conductor of heat and electricity
Malleable and ductile
resists corrosion (fine coat of Al2O3 forms)
Not very strong when pure - made stronger when mixed with other metals to form alloys
Generally non-toxic (not harmful to health)
What are the 2 main steps for making steels?
- Unwanted impurities are removed from the iron
- Other elements are added
What is used to remove impurities from iron? (making of steels)
Molten iron from a blast furnace is poured into an oxygen furnace, and a jet of oxygen is turned on
What does the oxygen do in an oxygen furnace (making of steels)?
Oxygen reacts with carbon, forming carbon monoxide and carbon dioxide gases, which are carried off.
Reacts with other impurities to form acidic oxides.
What is added after the oxygen has done its job in an oxygen furnace? (making of steels)
Calcium oxide
it is a basic oxide
reacts with silicon dioxide and other acidic oxides to give a slag that is skimmed off
Are all impurities removed from iron in the steel making process?
Depends on the type of steel
- for some yes, for some they just contain iron and carbon so carbon doesn’t need to be removed
Are all impurities removed from iron in the steel making process?
Depends on the type of steel
- for some yes, for some they just contain iron and carbon so carbon doesn’t need to be removed
What beneficial qualities does carbon give to iron in a steel?
Carbon makes steel stronger
What negative qualities can carbon give to iron in a steel?
Too much can make the steel brittle
therefore the carbon content is checked continually.
when it is correct the oxygen is turned off.
What does limestone mainly consist of?
Limestone consists mainly of calcium carbonate, CaCO3
What is lime?
calcium oxide
How is lime made?
manufactured from calcium carbonate by thermal decomposition:
How is lime made?
manufactured from calcium carbonate by thermal decomposition:
What is the chemical equation for the thermal decomposition of limestone?
CaCO3 → CaO + CO2
What is slaked lime?
calcium hydroxide
How is calcium hydroxide made?
made by adding a small amount of water slowly to calcium oxide
What is the chemical equation for the manufacture of slaked lime?
CaO + H2O → Ca(OH)2
What is limewater?
Limewater is a solution of calcium hydroxide in water
is limewater acidic or alkaline?
alkaline
What is formed when carbon dioxide is added to limewater?
The addition of carbon dioxide to calcium hydroxide produces the initial starting material, calcium carbonate
What is the chemical equation for the reaction between carbon dioxide and limewater?
CO2 + Ca(OH)2 → CaCO3 + H2O
Why does limewater turn cloudy upon contact with carbon dioxide?
turns cloudy due to calcium carbonate forming, which is an insoluble precipitate and the solution turns milky? cloudy
What do these 3 reactions constitute?
The limestone cycle
What does limestone help the manufacture of? 2
Limestone (calcium carbonate) is used in the manufacture of iron and cement
How does limestone help in the production of iron?
In the production of iron, limestone is added to the blast furnace where it decomposes to form lime (CaO) and carbon dioxide
The lime reacts with silica impurities to form calcium silicate, which floats to the top of the molten iron and is removed:
CaO + SiO2 → CaSiO3
- How is cement manufactured?
manufacture of cement
Cement is manufactured by heating a mixture of powdered limestone and clay in a rotary kiln
- What is added to the rotary kiln?
manufacture of cement
Once heated, calcium sulfate and water are added which produce cement
- What is cement? What is it made of?
manufacture of cement
Cement is a hardened, interlocked structure of calcium aluminate (Ca(AlO2)2 and calcium silicate (CaSiO3)
How can calcium carbonate be used?
CaCO3 is also used in treating excess acidity in soils and lakes where it is often preferred to lime because it does not make the water in the soil alkaline
how can lime be used?
Lime (calcium oxide) is used in lime mortar and in flue-gas desulfurisation
What does flue gas desulfurisation involve?
Flue-gas desulfurization involves spraying acidic sulfur dioxide emissions with jets of slaked lime to reduce pollution by neutralising these gases before they leave the factory chimneys
What may happen if too much lime is added when treating acidic soils?
It is also used in treating excess acidity in soils and lakes. If excess lime is used, however, the water in the soil may become too alkaline
How can slaked lime be used? 2
Slaked lime (calcium hydroxide) is used in treating acidic soils and neutralising acidic industrial wasted products
Formula for:
1-Limestone
2-Lime
3-Limewater
4-Carbon dioxide
Bond type for each one as well
1-CaCO3 (ionic)
2-CaO (ionic)
3-Ca(OH)2 (ionic)
4-CO2 (covalent)
Describe the experiment of thermal decomposition of limestone
LIMESTONE CYCLE
1-Heat a measured mass of limestone (CaCO3)
2-CaCO3 will break down to give calcium oxide (CaO) and carbon dioxide (CO2)
CaCO3 —> CaO + CO2
3-Add water (reaction is exothermic) to make slaked lime (another name for limewater). Ca(OH)2
4-Add more water (Reaction is exothermic) to make more limewater
5-Precipitation reaction to produce CO2
Uses of limestone (4)
Bathroom tiles
Bricks
Cement
Manufacturing of iron
Process of obtaining limestone
Quarrying
What is limestone composed of?
It’s a rock that is formed over many years from crushed animal skeletons
1-Equation for the Haber process
2-What type of reaction if the forward reaction? (Delta H)
3-What happens when you increase the pressure?
4-What happens when you increase the temperature?
1 - 3H2(g) + N2(g) 2NH3(g)
2 - Exothermic
3 - Moles of reactants : products is 4:2 so an increased pressure will favour products
4-Favours reactants as the forward reaction is exothermic
1-Equation for the Haber process
2-What type of reaction if the forward reaction? (Delta H)
3-What happens when you increase the pressure?
4-What happens when you increase the temperature?
1 - 3H2(g) + N2(g) 2NH3(g)
2 - Exothermic
3 - Moles of reactants : products is 4:2 so an increased pressure will favour products
4-Favours reactants as the forward reaction is exothermic
Conditions for Haber process (3)
Low temperature = 450 degrees C
High pressure = 200 atm
Iron (III) catalyst
1 - Raw materials of the Haber process (2)
2 - How do you obtain the raw materials?
1-Nitrogen and hydrogen
2-Nitrogen comes from the air and hydrogen is usually obtained through either cracking or reacting natural gases e.g. methane with steam
Uses of Ammonia (3)
Making medicines
Making fertilizers
Making explosives
What if the purpose of the Haber process?
To produce ammonia
Materials needed to produce ammonia
> Nitrogen from the air
> Hydrogen mainly from natural gas.
Conditions needed for the Haber process.
> High temp (about 450 degrees)
High pressure (about 200 atmospheres)
An iron catalyst.
Haber process in 5 steps.
- Gaseous nitrogen + hydrogen enter the machine.
- The gases are compresses to 200 atom and heated to 450 degrees.
- Passed over iron catalyst.
- Emerging mixture is cooled and the ammonia liquefies, separating it from he unseated nitrogen/hydrogen.
- Unreacted gases return to the beginning.
Use of ammonia
Fertilisers
Equilibrium
The point in a reversible reaction when the forwards and backwards rate of reaction are the same. Therefore, the amounts of substances present in the reacting mixture remain constant.
If the forward reaction produces more molecules of gas…
… an increase in pressure decreases the amount of products formed.
…. a decrease in pressure increases the amount of products formed.
If the forward reaction produces less molecules of gas…
… an increase in pressure increases the amount of products formed.
… a decrease in pressure decreases the amount of products formed.
When does changing the pressure affect a reaction’s equilibrium?
If there are different numbers of molecules of gases on either side of the equation.
If the forward reaction is exothermic…
… an increase in temperature decreases the amounts of product formed.
… a decrease in temperature increases the amount of products formed.
If the forward reaction is endothermic….
… an increase in temperature increases the amount of products formed.
… a decrease in temperature decreases the amount of products formed.
Why is a pressure of 200 atmospheres used in the Haber process?
The forward reaction produces less molecules of gas, so to get the maximum yield of ammonia, the pressure has to be as high as possible. However, above 200 atmo, special reaction vessels and pipes have to be used so that there is no danger of explosion. Therefore, to keep the process economical, a compromise is made.
Why is a temperature of 450 degrees used for the Haber process?
Because the forward reaction is exothermic, using a low temperature would increase the yield. However, doing so would make the process very slow and not commercially viable. Using a low temperature could also reduce the effectiveness of the iron catalyst.
How does the use of a catalyst affect the Haber process?
It speeds up both the forwards and backwards reaction, but has no effect on the actual yield.
