Chemistry IGCSE > metals > Flashcards
metals Flashcards
compare the thermal conductivity metals vs non metals
metals- good conductor of heat
non-metals- poor conductor
compare the physical properties of non metals vs metals
metals- maellable, ductile, shiny
non metals- quite brittle, not ductile not maellable
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
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
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)
State the order of the reactivity series
potassium, sodium, calcium, magnesium,
aluminium, carbon, zinc, iron, hydrogen, copper,
silver, gold
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-
