2.3 Metals and extraction

Question 1

What are ores?

Answer 1

Ores are raw minerals found in Earth’s crust that contain metal compounds such as Iron Oxide (Fe₂O₃) or bauxite (Al₂O₃).
The more reactive a metal is, the harder it is to separate it from it’s formula.
- Iron is less reactive so you can use a displacement reaction (Reduction reaction) to get a pure metal.
- Aluminium is more reactive and can be separated from it’s compound using electrolysis when molten.
- Gold, platinum and sliver ore are found pure as they are very unreactive.

Question 2

List the reactivity series.

Answer 2

Potassium- Parry (Most reactive)
Sodium- Said
Calcium- Cancel
Magnesium- Mocks
Aluminium- And 
(Carbon- Car)-Gas
Zinc- Zoos
Iron- In
Tin- The
Lead- Lead.
(Hydrogen- Harrison)-Gas
Copper- Coppen
Silver- Sings 
Gold- Graham's 
Platinum- Pieces (Least Reactive) ;)

Question 3

What is the process of extracted iron using a blast furnace?

Answer 3

1) Raw materials including iron ore, coke (carbon) and limestone are added at the top of a furnace.
2) Blasts of hot air are blown in at the bottom of the furnace and the oxygen in the air reacts with coke to form carbon monoxide - this reaction is very exothermic. (2C + O₂ → 2CO)
3) The carbon monoxide rises up the furnace and reacts with iron (III) oxide to form iron (Fe₂O₃ + 3CO → 2Fe + 3CO₂)
4) This molten iron runs out of the bottom of the furnace.
5) It’s either used to make steel or placed into moulds to solidify.

Question 4

Why is limestone added to a blast furnace?

Answer 4

It’s added to remove any impurities such as sand (Silicon Dioxide)
1) Limestone thermally decomposes to form Calcium Oxide and Carbon Dioxide (CaCO₃ → CaO + CO₂)
2) Calcium neutralises the sand to form slag
(CaO + SiO₂ → CaSiO₃)
Slag can be used in construction and a whole range of tasks.

Question 5

What is the overall reaction in a blast furnace?

Answer 5

Fe₂O₃ + 3CO → 2Fe +3CO₂
Fe₂O₃ to 2Fe is Reduction
3CO to 3CO₂ is Oxidation

Question 6

What is electrolysis and what is an electrolyte.

Answer 6

A process where ionic substances (either molten or in a aqueous solution) are split apart using large amounts of electricity.
The electrolyte is the ionic substance being separated.

Question 7

What is OILRIG

Answer 7

Oxidation 
Is
Loss (of electrons)
Reduction 
Is 
Gain (of elections)

Question 8

How is electrolysis used to create pure aluminium?

Answer 8

1) Aluminium oxide is heated (with the assistance of cryolite that lowers the melting point) until it melts.
2) This allows positively charged aluminium ions (Al³⁺) to move towards the negatively charged cathode (at the bottom).
3) The Aluminium ion gains 3 electrons ( Al³⁺ + 3e⁻ → Al) which neutralizes it into a normal atom where it’s filtered out
4) Negatively charged Oxygen (O²⁻) ions are attracted to the anode where it gains 2 electrons (2O²⁻ → O₂ + 4e⁻)
5) The overall reaction is 2Al₂ O₃ → 4Al + 3O₂
NOTE: The graphite anode losses mass over time as oxygen reacts with carbon to form Carbon Dioxide (C+O₂→ CO₂)

Question 9

What is the chemical formula for a (metal) sulphate?

Answer 9

(Metal)SO₄

Question 10

What is the purpose of the cryolite in the creation of pure aluminium?

Answer 10

To reduce the boiling boing of aluminium which also reduces the energy needed to start the reaction.

Question 11

Why does the mass of the anode reduce over time in the formation of pure aluminium?

Answer 11

When the 2O²⁻ carry out oxidation at the graphite anode (2O²⁻ → O₂ + 4e⁻) some O₂ reacts with the graphite (Which is carbon) to form carbon dioxide (C + O₂ → CO₂)

Question 12

What is the chemical formulae for Slag?

Answer 12

CaSiO₃

Question 13

What happens in a thermite reaction?

Answer 13

Iron Oxide + Aluminium (+ Heat) → Iron + Aluminium Oxide
Fe₂O₃ + 2Al → Al₂O₃ + 2Fe
This displacement reaction is VERY exothermic.

Question 14

What is the reaction inside a blast furnace to form carbon monoxide?

Answer 14

2C + O₂ → 2CO

Coke + Oxygen → Carbon Monoxide

Question 15

What is the reaction inside a blast furnace to form Iron?

Answer 15

Fe₂O₃ + 3CO → 2Fe + 3CO₂

Iron oxide + Carbon Monoxide → Iron + Carbon Dioxide

Question 16

What is the process of forming slag in the blast furnace?

Answer 16

1) Limestone thermally decomposes to form Calcium Oxide and Carbon Dioxide (CaCO₃ → CaO + CO₂)
2) Calcium reacts with sand to form slag
(CaO + SiO₂ → CaSiO₃)
Slag can be used in construction and a whole range of tasks.

Question 17

What is slag used for?

Answer 17

Can be used in construction and a whole range of tasks.

Question 18

What is the chemical formula for sand?

Answer 18

SiO₂ (Silicon dioxide)

Question 19

What is the general process for electrolysis (Including electron transfer)?

Answer 19

1) Electrolyte substance is separated into its positive and negative ions

2) Positive ions (Cations) are attracted to the negatively charged cathode (e.g. Al³⁺ + 3e⁻ → Al)
The ion GAINS electrons (Reduction)

3) Negative ions (Anions) are attracted to the positively charged anode (e.g. 2O²⁻ → O₂ + 4e⁻).
The ion LOSES electrons to gain a full outer shell (Oxidation).

4) The ionic substance is now slip into neutral atoms.

Question 20

What is the difference between electrolysis with dissolved salts with reactive metals (e.g. sodium) compared to other electrolysis.

Answer 20

There competition at the cathode between the positive reactive metal and hydrogen ion (from the water). Hydrogen, with no electrons, gains electrons more easily so hydrogen gas is produced. (2H⁺ + 2e⁻ → H₂)

Question 21

What is the main formula in the electrolysis of water that explains the different water levels in each tube?

Answer 21

2H₂O → 2H₂ + O₂

4 hydrogen compared to 2 oxygen.

Question 22

What happens at the cathode with the electrolysis of water?

Answer 22

2H⁺(aq) + 2e⁻ → H₂(g)

A reduction reaction

Question 23

What happens at the anode with electrolysis of water?*

Answer 23

2OH⁻(aq)→ O₂(g) + 2H⁺ + 4e⁻
An oxidation reaction.
(Extra 2 hydrogen- still more hydrogen in the end-2:1 ration)

Question 24

What elements are added to create stainless steal?

Answer 24

Chromium and Carbon

Question 25

What are transition metals and their properties?

Answer 25

Metals found between group 2 and 3 (Middle of periodic table)

• Form coloured compounds
• Good conductors of electricity
• Malleable
• Less reactive metals
• High melting points (apart from mercury)
• Varying charges e.g. Fe2+ and Fe3+ or Cu+ and Cu2+

Question 26

What is an inert electrode?

Answer 26

An electrode that doesn’t react with the electrolyte

Question 27

What happens at the cathode when electrolysing aqueous solutions of ionic compounds?

Answer 27

If the metal (positive ion) is less reactive than hydrogen (in the reactivity series) then that metal will be formed at the cathode. If it’s more reactive, hydrogen gas will be produced. (2H⁺(aq) + 2e⁻ → H₂(g)) and the metal will remain in the solution.

Question 28

What happens at the anode when electrolysing aqueous solutions of ionic compounds?

Answer 28

Simple ions (Br⁻, Cl⁻) will form as normal but compound ions (NO₃⁻,CO₃⁻, SO₄⁻) will remain in the solution and hydroxide will instead form oxygen (2OH⁻(aq)→ O₂(g) + 2H⁺ + 4e⁻)

Question 29

What is brine?

Answer 29

Sodium Chloride solution (Water)

Question 30

What is the set up for electroplating a material?

Answer 30

Cathode (-)- The object you want electroplated
Anode(+)- Metal you want to code the object with (cathode)
Electrolyte- Solution of the coating metal (E.g. Metal Nitrate or sulfate)

Question 31

What is the set up for the purification of copper and what happens?

Answer 31

Anode(+)- Impure copper
Cathode(-)- Pure Copper
Electrolyte- Copper (II) sulfate solution

• Once the two rods are charged with a battery, the copper atoms in the anode lose their electrons (Cu → Cu²⁺ + 2e⁻) and become positively charged ions that move to the cathode where they become atoms again (Cu²⁺ + 2e⁻ → Cu)
  As a result:
  The pure rod increases in mass and the impure rod deteriorates to an ‘anode sludge’.

Question 32

How do we create sodium hydroxide?

Answer 32

Brine (Sodium Chloride) in an aqueous solution.
Chlorine gas forms at anode and Hydrogen gas at cathode leaving Sodium and hydroxide ions which ionically bond to create sodium hydroxide

This is done on a commercial scale using sea water
Production of:
Soaps
Explosives
paper
dyes
Chemical tests for transition metals ( Fe2+ and Fe3+ or Cu+ and Cu2+)