Extraction of metals and reduction: identify the substances which are oxidised or reduced in terms of gain or loss of oxygen.

Q: How do I revise Extraction of metals and reduction: identify the substances which are oxidised or reduced in terms of gain or loss of oxygen. for GCSE?

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Q: Is this Extraction of metals and reduction: identify the substances which are oxidised or reduced in terms of gain or loss of oxygen. guide aligned to the AQA specification?

Yes. This guide is linked to the Extraction of metals and reduction: identify the substances which are oxidised or reduced in terms of gain or loss of oxygen. topic in the AQA GCSE specification.

In a reaction, a substance is oxidised if it gains oxygen and reduced if it loses oxygen.

Study notes

From the checked teaching notes for this specification point.

The idea

What earns the marks

State that oxidation is gain of oxygen and reduction is loss of oxygen.
Compare the oxygen content of a substance on the reactant and product sides of a given equation.
Correctly label a named substance as oxidised when it gains oxygen, or reduced when it loses oxygen.
Apply the definition to extraction reactions, such as reduction of a metal oxide by carbon.
Use the formulae and state symbols in an equation to track oxygen atoms reliably.

Common mistakes and how to put them right

Confusing oxidation with reduction.
Put it right: 'oxidation is gain of oxygen' and 'reduction is loss of oxygen'.
Assuming the metal is always the oxidised substance.
Put it right: Check each formula for oxygen gain or loss rather than relying on the name.
Ignoring oxygen in product formulae such as CO₂ or H₂O.
Put it right: Count oxygen atoms in every substance on both sides.

Exam tips

Underline the oxygen in each formula before deciding which substance gains or loses it.
Write a brief 'gains O' or 'loses O' next to each substance to justify your identification.
If asked to explain, link the change in oxygen directly to the terms oxidised and reduced.

Try the lesson

The start of the Extraction of metals and reduction: identify the substances which are oxidised or reduced in terms of gain or loss of oxygen. lesson, made from checked teaching notes for this specification point.

Have a go first

In the reaction 2Mg + O₂ → 2MgO, which substance is oxidised?

Tip: press 1 to 4 to choose

Listen

In a reaction, a substance is oxidised if it gains oxygen and reduced if it loses oxygen. This oxygen-based definition applies to reactions such as the reduction of metal oxides with carbon. For example, in 2Fe₂O₃ + 3C → 4Fe + 3CO₂, iron(III) oxide loses oxygen, so it is reduced, while carbon gains oxygen, so it is oxidised. To identify each substance, compare its formula on both sides of the equation and track oxygen atoms. If a substance gains oxygen, label it oxidised; if it loses oxygen, label it reduced. The same substance cannot normally be both in one simple equation. This skill underpins understanding of extraction of metals, where a metal oxide is reduced to the metal. A strong answer earns marks for these points. State that oxidation is gain of oxygen and reduction is loss of oxygen. Compare the oxygen content of a substance on the reactant and product sides of a given equation. Correctly label a named substance as oxidised when it gains oxygen, or reduced when it loses oxygen. Apply the definition to extraction reactions, such as reduction of a metal oxide by carbon. Exam tip: Underline the oxygen in each formula before deciding which substance gains or loses it.

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