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Chemistry GCSE > 2.3 - Metals and their extraction > Flashcards

2.3 - Metals and their extraction Flashcards

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1
Q

What is metal extraction?

A

Metals are extracted from ores which are rocks containing metal compounds found in the earth’s crust
These metals can be extracted using chemical reactions

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2
Q

What is the relationship between metal reactivity and extraction?

A

The more reactive the metal is, the more stable its metal compound so the harder it is to extract from pure metal - i.e. gold is very uncreative so is found in pure form.

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3
Q

What are the extraction processes depending on the reactivity of the metal

A

Electrolysis - for metals more reactive than carbon
Reduction with carbon - for metals less reactive than carbon ( cheaper process than electrolysis )
Metals less reactive than hydrogen are found in the native form.

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4
Q

Where is carbon and hydrogen in the reactivity series?

A

Carbon - between Al and Zinc

Hydrogen - between Lead and Copper

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5
Q

More reactive metals have a greater tendency to ____ (lose/gain) electrons and form positive ions

A

lose

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6
Q

How can you remember the reactivity series

A 
Please        - Potassium 
Stop            - Sodium
Calling        - Calcium
Me              - Magnesium
A                 - Aluminium 
Carless       - (Carbon)
Zebra          - Zinc
Instead       - Iron
Try               - Tin
Learning     - Lead
How             - (Hydrogen)
Copper         - Copper
Saves            - Silver
Gold              - Gold
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7
Q

What observations determine where these metals are ranked in the reactivity series?

A

How these elements react with water, acids and steam

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8
Q

Why is it sometimes difficult to rank aluminium in the reactivity series?

A

Because its protective aluminium oxide layer makes it appear to be less reactive than it really is. When this layer is removed, the observations are more reliable.

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9
Q

What is a displacement reaction and how is it useful?

A

When a more reactive metal displaces a less reactive metal from a compound
Can be used to investigate the relative reactivities of metals

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10
Q

What is a thermite reaction?

A

A displacement reaction between aluminium and iron oxide producing aluminium oxide and iron. It releases enough heat to melt the iron so it can used for joining railway tracks together

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11
Q

In a thermite reaction give the chemical reaction formula?

What is oxidised and what is reduced?

A

aluminium + iron(III) oxide → iron + aluminium oxide

2Al + Fe2O3 → 2Fe + Al2O3

iron(III) oxide is reduced
aluminium is oxidised

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12
Q

What is oxidation?

A

Gain of oxygen
Loss of electrons
Loss of Hydrogen
The species oxidised is known as the reducing agent

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13
Q

What is reduction?

A

Loss of oxygen
Gain of electrons
Gain of hydrogen
The species reduced is known as the oxidising agent

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14
Q

A more reactive metal will displace a less reactive metal from a solution of one of its salts. For example:

magnesium + copper(II) sulfate → copper + magnesium sulfate

Mg(s) + CuSO4(aq) → Cu(s) + MgSO4(aq)

What happens in this reaction with respect to colour change?

A

In this reaction, the blue colour of the copper(II) sulfate fades as it is used up (magnesium sulfate solution is colourless). We would also see copper metal (red/brown solid) forming.

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15
Q

What is an oxidising agent?

A

The chemical that causes oxidation by providing oxygen

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16
Q

What is a reducing agent?

A

Causes the other chemical to be reduced by removing oxygen

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17
Q

aluminium + iron(III) oxide → iron + aluminium oxide

2Al + Fe2O3 → 2Fe + Al2O3

In this reaction what chemical is the reducing agent and which chemical is the oxidising agent?

A

Aluminium has been oxidised. This means that the iron(III) oxide is the oxidising agent. We can also see that the iron(III) oxide has been reduced. This means that the aluminium is the reducing agent

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18
Q

What 4 raw materials are used in extracting iron in a blast furnace?

A

1) Iron ore (haematite)
2) Coke
3) Limestone
4) Air

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19
Q

What does Iron ore (Haematite) contain and why is it used?

A 
Contains Iron(III) oxide (Fe2O3)
It is the compound that the iron is extracted from
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20
Q

What does coke contain and why is it used?

A

Contains carbon

It is used as a fuel and reacts to form carbon monoxide (needed to reduce the iron(III) oxide)

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21
Q

What does limestone contain and why is it used?

A

Contains calcium carbonate (CaCO3)

Helps to remove acidic impurities from the iron by reacting with them to form molten slag

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22
Q

What does air contain and why is it used?

A 
Contains oxygen (O2)
Provides oxygen to allow the coke to burn, and so produces heat
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23
Q

What is the 3 steps of extracting Iron from a blast furnace?

A

1) Hot air (oxygen) reacts with the coke (carbon) to produce carbon dioxide and heat energy to heat up the furnace.

C(s) + O2(g) → CO2(g)

2) More coke is added to the furnace and reduces the carbon dioxide into carbon monoxide, a good reducing agent.

CO2(g) + C(s) → 2CO(g)

3) iron(III) oxide is reduced.

iron(III) oxide + carbon → iron + carbon dioxide

2Fe2O3(s) + 3C(s) → 4Fe(l) + 3CO2(g)

24
Q

In the blast furnace, it is so hot that carbon monoxide can be used, in place of carbon, to reduce the iron(III) oxide:

What is the equation for this reaction?

A

iron(III) oxide + carbon monoxide → iron + carbon dioxide

Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(g)

25
Q

How are impurities removed from the iron ore in a blast furnace?

A

The main impurity is silicon dioxide (sand)
Limestone undergoes thermal decomposition to form calcium oxide
The calcium oxide reacts with the silicon dioxide to form calcium silicate which can be removed from the furnace
This is a neutralisation reaction

26
Q

Why is removing impurities from iron in a blast furnace a neutralisation reaction?

A

Calcium oxide is basic (as it is a metal oxide) and silica is acidic (as it is a non-metal oxide).

27
Q

Give some factors that influence where a blast furnace plant should be built?

A

1) near the coast to allow for the import of raw materials
2) near roads and railway lines to allow for products to be taken to where they are needed
3) near a town or city, so that workers have somewhere to live close-by
4) away from built-up areas, so that the noise and pollution of the site do not affect the local population

28
Q

Where are transition metals found in a periodic table?

A

In the central area of the periodic table

In-between groups 2 - 3

29
Q

What are the properties of the majority of transition metals?

A

They form coloured compounds.
They are good conductors of heat and electricity.
They are malleable, ie can be hammered or bent into shape easily.
They are less reactive than alkali metals, such as sodium.
They have high melting points – but mercury is a liquid at room temperature.
They are usually hard and tough.
They usually have high densities.
They can form ions with different charges. For example, iron can lose two electrons to form Fe2+ ions or it can lose three electrons to form Fe3+ ions. Another example is Cu+ and Cu2+

30
Q

Solutions containing transition metal ions often have characteristic colours. What are the colours of the solutions containing the following ions:

Fe2+(aq)
Fe3+(aq)
Cu2+(aq)

A

Fe2+(aq) → pale green

Fe3+(aq) → brown

Cu2+(aq) → blue

31
Q

How does electrolysis work?

A

When a metallic compound is melted or dissolved, the ions are free to move within the liquid or solution
Passing a current through the molten liquids or solutions will mean that the solution is broken down into elements

32
Q

What happens during electrolysis?

A

Positively-charged ions move to the negative electrode (cathode). They receive electrons and are reduced.
Negatively-charged ions move to the positive electrode (anode). They lose electrons and are oxidised.
The substance that is broken down is called the electrolyte.

33
Q

What happens during the electrolysis of molten ionic compounds (e.g. lead bromide)?

A

Pb2+ ions are positively charged so these ions move to the cathode and lead is produced at the cathode
The half equation at the cathode is
Pb2+ (aq) + 2e- –> Pb (s)
Br- ions are negatively charged so these ions move to the anode where two bromide ions lose an electron to form liquid bromine
The half equation at the anode is:
2Br- (aq) –> Br2 (l) + 2e-

34
Q

What does a half equation show you?

A

A half-equation shows you what happens at one of the electrodes during electrolysis. Electrons are shown as e–. A half-equation is balanced by adding, or taking away, a number of electrons equal to the total number of charges on the ions in the equation

35
Q

What does OIL RIG stand for

A 
Oxidation (gain of oxygen)
 Is 
Loss of electrons, 
Reduction 
Is 
Gain of electrons. (loss of oxygen)
36
Q

Explain the process of industrial extraction of aluminium?

A

Aluminium oxide is melted so electricity can be passed through it.
Aluminium oxide is dissolved in cryolite which is a substance that lowers the melting point.
Aluminium metal forms at the negative electrode and sinks to the bottom of the tank.
Oxygen forms at the positive electrode and reacts with the carbon in the graphite electrodes forming CO2.
The positive electrode has to be replaced often to account for the reaction of carbon and oxygen.

37
Q

Give some factors that influence where a aluminium extraction plant should be built?

A

1) In close proximity to a power station, in order to provide the large supply of electricity needed for the electrolysis
2) Near the coast to allow for the import of raw materials
3) Near roads and railway lines to allow for the product to be taken to where it is needed
4) Near a town or city, so that workers have somewhere to live close by
5) Away from built-up areas, so that the noise and pollution of the site do not affect the local population

38
Q

Why are carbon electrodes used in electrolysis?

A

High melting point

Inert (they will not react with the reactants and products during electrolysis)

39
Q

What is the test for metal ions?
Copper (II) gives a ____ precipitate
Iron (II) gives a _____ precipitate
Iron (III) gives a _____ precipitate

A

blue
green
brown

40
Q

The metal is formed at the _____ (positive, negative) electrode because that is where the _____ (positive, negative) metal ions are attracted.

The non-metal element is formed at the _____ (positive, negative) electrode where the _____ (positive, negative) non-metal ions are attracted

A

negative
positive
positive
negative

41
Q

Electrolysing water splits the water molecules (H2O) into hydrogen (H2) and oxygen (O2) molecules. What is the equation for this reaction?

A

water → hydrogen + oxygen

2H2O(l) → 2H2(g) + O2(g)

42
Q

In electrolysing of water what happens at the cathode and anode in respect to oxidation and reduction?

A

At the negative electrode (cathode) a reduction reaction occurs.
4H+(aq) + 4e– → 2H2(g)

At the positive electrode (anode) an oxidation reaction occurs.
4OH–(aq) → 2H2O(l) + O2(g) + 4e–

43
Q

Why can electrolysing aqueous solutions of ionic compounds be more complicated than electrolysing molten compounds?

A

Because the water molecules can provide hydrogen ions (H+) and hydroxide ions (OH–), in addition to the ions from the ionic compounds.

44
Q

Metal ions and hydrogen ions are positively charged. Whether you get the metal or hydrogen during electrolysis depends on the position of the metal in the reactivity series:

the metal will be produced if it is ____ (more/less) reactive than hydrogen
hydrogen will be produced if the metal is ____ (more/less) reactive than hydrogen

A

less

more

45
Q

In electrolysis what element will be given off at positive electrode when the negative ion in the solution is:

Chloride, Cl–
Bromide, Br–
Iodide, I–

A

Chlorine, Cl2
Bromine, Br2
Iodine, I2

46
Q

Remember:

A

The electrolysis of sodium chloride solution will produce chlorine gas at the anode and hydrogen gas at the cathode.

at the anode, 2Cl– → Cl2 + 2e– (oxidation)
at the cathode, 2H+ + 2e– → H2 (reduction)
During the electrolysis, hydrogen and chloride ions are removed from solution whereas sodium and hydroxide ions are left behind in solution. This means that sodium hydroxide is also formed during the electrolysis of sodium chloride solution. This process is carried out on an industrial scale using sea water to produce hydrogen gas, chlorine gas and sodium hydroxide solution.

47
Q

What is an alloy?

A

An alloy is a mixture of two or more elements, where at least one element is a metal.

48
Q

What are the properties of

Mild steel - Carbon and iron
Tool steel - Tungsten and iron
Stainless steel - Chromium and iron

A

Easy to bend and pull into wires
Can be heated to high temperatures
Hard, does not rust easily

49
Q

Electrolysis is used to electroplate objects (coat them with a thin layer of metal). This is useful for coating a cheaper metal with a more expensive one, such as copper or silver.

How it works:

The _____ (positive, negative) electrode should be the object to be electroplated.

The _____ (positive, negative) electrode should be the metal that you want to coat the object with.

The electrolyte should be a solution of the coating metal, such as its metal nitrate or sulfate.

A

negative

positive

50
Q

What happens during electrolysis of purifying copper?

A

Electricity is passed through solutions containing copper compounds, such as copper(II) sulfate

The anode (positive electrode) is made from impure copper and the cathode (negative electrode) is made from pure copper.

The anode loses mass as copper dissolves, and the cathode gains mass as copper is deposited.

51
Q

What are the half equations in the electrolysis of copper (II) chloride

at the cathode…
at the anode…

A

At the cathode since copper is less reactive than hydrogen, copper ions are reduced to solid copper: Cu → Cu2+ + 2e–

At the anode chloride ions are oxidised: 2Cl- → Cl + 2e-

52
Q

What are the properties and uses of Iron?

A

Malleable
An alloy, steel, can be formed from iron and carbon
Steel is harder and stronger than Iron and less likely to rust
Used to build cars and used in the construction industry

53
Q

What are the properties and uses of aluminium?

A

Low density
Light weight for its size
Resists corrosion due to the very thin layer that oxidises on the surface
Used in aircraft, trains, overhead power cables, saucepans, cans

54
Q

What are the properties and uses of copper?

A

Good conductor of electricity and heat
Malleable
Resistant to corrosion (very unreactive)
Used in water pipes, electrical wires, decorative goods

55
Q

What are the properties and uses of titanuim?

A

Low density
Light weight for size
Resists corrosion
Good conductor of heat but poor conductor of electricity
Used in drill bits, fighter aircraft, golf clubs, medical implants

Chemistry GCSE (6 decks)

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