# Tin(IV) oxide can be reduced by heating it with carbon. The equation for this reaction is: SnO₂ + 2C → Sn + 2CO. Explain why tin(IV) oxide is reduced in this reaction and why carbon is oxidised. In your answer, use both the gain/loss of oxygen definition and the gain/loss of electrons definition.

> Edexcel A-Level Chemistry (9CH0) — 3.1 Oxidation and reduction · Explain · 5 marks

> Tin has been extracted from tin(IV) oxide by heating with carbon for thousands of years. The equation for this reaction is: SnO₂ + 2C → Sn + 2CO.

## Mark scheme (5 marks)

1. Tin(IV) oxide is reduced because it loses oxygen (from SnO₂ to Sn)
2. Carbon is oxidised because it gains oxygen (from C to CO)
3. Reduction is the gain of electrons, so tin ions (Sn⁴⁺) gain electrons to form tin metal
4. Oxidation is the loss of electrons, so carbon atoms lose electrons during the reaction
5. Carbon acts as a reducing agent because it causes the reduction of tin(IV) oxide (by providing electrons or removing oxygen)

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