3.3.4 - metal extraction

Question 1

What are ores?

Answer 1

Most metals are found in the Earth’s crust as compounds in rocks called ores.

Ores typically contain oxides or sulfides.

Question 2

Give an example of an ore.

Answer 2

Iron ore (haematite, Fe₂O₃)

Haematite is a primary source of iron.

Question 3

What are native metals?

Answer 3

Some unreactive metals like gold, silver, and platinum are found pure in the ground.

These metals do not react with other elements.

Question 4

What factor determines the method of metal extraction?

Answer 4

The position in the reactivity series.

Metals are extracted using different methods based on their reactivity.

Question 5

How are highly reactive metals extracted?

Answer 5

By electrolysis (using electricity to split compounds).

Example: Extraction of aluminium from bauxite (Al₂O₃).

Question 6

What is the extraction method for medium reactive metals?

Answer 6

Carbon reduction (using carbon to remove oxygen).

Example: Extraction of iron from haematite (Fe₂O₃).

Question 7

What is the extraction method for unreactive metals?

Answer 7

Found as native metals (no extraction needed).

Example: Gold nuggets in the ground.

Question 8

Describe the process of electrolysis in metal extraction.

Answer 8

The ore is melted into a liquid, and electricity splits the metal compound, extracting pure metal.

This method is expensive due to high electricity use.

Question 9

What is the process of carbon reduction for medium reactive metals?

Answer 9

The ore is heated with carbon in a blast furnace, where carbon removes oxygen from the metal oxide, leaving pure metal.

Example: Iron extraction from haematite (Fe₂O₃).

Question 10

What is the chemical reaction for iron extraction from haematite?

Answer 10

Fe₂O₃ + 3C → 2Fe + 3CO

This reaction shows carbon reducing iron oxide.

Question 11

What are redox reactions in the context of metal extraction?

Answer 11

They involve reduction (metal gains electrons) and oxidation (oxygen is removed from the ore).

Example: Iron extraction (Fe₂O₃ + C).

Question 12

What does reduction mean in metal extraction?

Answer 12

Metal gains electrons and is extracted.

This process involves the removal of oxygen.

Question 13

What does oxidation mean in metal extraction?

Answer 13

Oxygen (or another element) is removed from the ore.

In iron extraction, carbon is oxidized.

Question 14

True or False: Oxidation Is Loss (of electrons) and Reduction Is Gain (of electrons).

Answer 14

True

This is a mnemonic to remember the concepts of redox reactions.