AQA GCSE FOUNDATION Chemistry: Extracting Metals

Extracting Metals: AQA GCSE Foundation Chemistry

This tutorial covers the methods used to extract metals, focusing on electrolysis and reduction with carbon.

Why Do We Need to Extract Metals?

Metals are found in the Earth's crust in the form of ores. Ores are rocks that contain a metal compound. We need to extract metals from their ores because they are rarely found in their pure form.

Methods of Extracting Metals

The method used to extract a metal depends on its reactivity.

• Reactive metals: Reactive metals, such as sodium and potassium, are found at the top of the reactivity series. They cannot be extracted by reduction with carbon. Instead, they are extracted by electrolysis.

• Less reactive metals: Less reactive metals, such as iron and zinc, are found lower down the reactivity series. They can be extracted by reduction with carbon.

Electrolysis

Electrolysis is a process that uses electricity to break down a compound. It is used to extract reactive metals from their molten compounds.

How electrolysis works:

1. The molten metal compound is placed in an electrolytic cell.
2. Electrodes are inserted into the molten compound.
3. An electric current is passed through the molten compound.
4. The positively charged metal ions move towards the negatively charged electrode (cathode).
5. The negatively charged non-metal ions move towards the positively charged electrode (anode).
6. At the cathode, the metal ions gain electrons and are reduced to form the pure metal.
7. At the anode, the non-metal ions lose electrons and are oxidised to form the non-metal.

Example: The extraction of sodium from sodium chloride.

2NaCl(l) --> 2Na(l) + Cl2(g)

• At the cathode: Na+ + e- --> Na
• At the anode: 2Cl- --> Cl2 + 2e-

Reduction with Carbon

Reduction with carbon is a process that uses carbon to remove oxygen from a metal oxide. It is used to extract less reactive metals from their ores.

How reduction with carbon works:

1. The metal oxide is heated strongly with carbon.
2. Carbon is a good reducing agent. It reacts with the oxygen in the metal oxide to form carbon dioxide.
3. The metal is left behind in its pure form.

Example: The extraction of iron from iron oxide (hematite).

Fe2O3(s) + 3C(s) --> 2Fe(l) + 3CO(g)

• The carbon reacts with the oxygen in the iron oxide to form carbon monoxide.
• The carbon monoxide then reduces the iron oxide to iron.

Key Points to Remember

• The reactivity series is a useful tool for determining which method is best for extracting a metal.
• Electrolysis is used to extract reactive metals.
• Reduction with carbon is used to extract less reactive metals.
• Both methods require energy input.
• The extraction of metals has a significant impact on the environment.

This tutorial provides a basic understanding of the methods used to extract metals. For a more in-depth understanding, refer to your AQA GCSE Foundation Chemistry textbook or consult your teacher.