Extraction of Metals

Question 1

What is an ore?

Answer 1

A natural substance that a metal can be economically extracted from

Question 2

Which types of metals are often found in ores?

Answer 2

Sulfides or oxides

Question 3

Why is sulfur dioxide bad?

Answer 3

It causes acid rain which can damage limestone buildings, harm aquatic life and plants.

Question 4

What does ‘roasting’ mean?

Answer 4

Ore is heated in plenty of air (oxygen)

Question 5

What is reduction?

Answer 5

Gain of electrons

Question 6

What is a reducing agent?

Answer 6

Something that donates electrons and gets oxidised

Question 7

What is oxidation?

Answer 7

Loss of electrons

Question 8

What is an oxidising agent?

Answer 8

Something that accepts electrons and gets reduced

Question 9

Balanced equation of the reduction of iron(III) oxide using carbon monoxide

Answer 9

Fe₂O_{3 (s)}+ 3CO_(g) → 2Fe_(l)+ 3CO_{2 (g)}

Question 10

Where does the reduction of metal oxides take place in?

Answer 10

Blast furnace

Question 11

What do the roman numerals after an element show? E.g. Copper(II) oxide

Answer 11

The oxidation state of that element in that particular compound

Question 12

Define oxidation state (AKA oxidation number)

Answer 12

Total number of electrons an element has donated or accepted

Question 13

Balanced equation of the reduction of manganese(IV) oxide using carbon (as coke)

Answer 13

MnO_{2 (s)} + C_(s) → Mn _(l) + CO_{2 (g)}

Question 14

Why is carbon not used for the reduction of aluminium?

Answer 14

Aluminium is too reactive and requires very high temperatures for the reduction, making it too expensive

Question 15

How is aluminium extracted from its ore?

Answer 15

Electrolysis

Question 16

Why does the electrolyte have to be a liquid?

Answer 16

So the ions are free to move

Question 17

What happens at the anode?

Answer 17

Oxide ions lose electrons and are oxidised, producing oxygen gas

Question 18

Why is the anode frequently replaced?

Answer 18

Because the carbon reacts with the oxygen produced

Question 19

Write the half equation of aluminium at the cathode during electrolysis

Answer 19

Al³⁺ + 3e^- → Al

Question 20

Why is carbon not used to extract titanium?

Answer 20

Because you get titanium carbide, ruining its purity and properties

Question 21

How is titanium extracted from its ore?

Answer 21

1. Ore is converted to TiCl₄ at about 900°C using C and Cl gas
2. TiCl₄is purified by fractional distillation
3. Cl gas gets reduced in furnace at almost 1000°C with a more reactive metal

Question 22

Write the two equations/steps of extracting titanium using magnesium

Answer 22

1) TiO_{2 (s)} + 2Cl_{2 (g)} + 2C _(s) → TiCl_{4 (g)} + 2CO_(g)
2) TiCl_{4 (g)}+ 2Mg_(l) → Ti_(s) +2MgCl_{2 (l)}

Question 23

Why is inert atmosphere argon used in the blast furnace?

Answer 23

To prevent TiCl₄, reducing agent and titanium metal from reacting with O₂ or water vapour from the air

Question 24

Balanced equation of the extraction of tungsten

Answer 24

WO_{3 (s)} +3H_{2 (g)} → W_(s) + 3H₂O_(g)

Question 25

Why is carbon not used to extract tungsten?

Answer 25

Because it can leave **impurities**, making the metal more **brittle**

Question 26

Problem with using hydrogen in a blast furnace?

Answer 26

Hydrogen is highly **explosive** when mixed with air

Question 27

Temperature for the reduction of MnO₂?

Answer 27

About **1200°C** (much higher than iron(III) oxide)