Silver nitrate solution reacts with copper metal. In this reaction, silver ions gain electrons to form silver atoms, and copper atoms lose electrons to form copper ions. Explain what has been oxidised and what has been reduced in this reaction, and describe what the terms oxidation and reduction mean in terms of electron transfer.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
When a piece of copper metal is placed into silver nitrate solution, the solution gradually loses its colourless appearance and silver grey solid begins to coat the copper. The overall reaction can be represented as: Cu + 2Ag⁺ → Cu²⁺ + 2Ag
Model answer (5 marks)
Copper atoms have been oxidised to Cu²⁺.
Oxidation is the loss of electrons.
Silver ions have been reduced to Ag atoms.
Reduction is the gain of electrons.
Both oxidation and reduction occur simultaneously – this is a redox reaction.
Oxidation is the loss of electrons.
Silver ions have been reduced to Ag atoms.
Reduction is the gain of electrons.
Both oxidation and reduction occur simultaneously – this is a redox reaction.
Examiner tips
- Use the word ‘oxidised’ for copper and ‘reduced’ for silver to match the mark scheme.
- Define oxidation as loss of electrons and reduction as gain of electrons – the examiner looks for these exact phrases.
- Show that the two processes happen together to justify the term ‘redox’.
Common mistakes
- Confusing ‘oxidised’ with ‘reduced’ for copper or silver.
- Omitting the definition of oxidation/reduction or using vague terms like ‘change in state’.
- Failing to mention that both processes occur simultaneously.
Mark scheme (5 marks)
- Copper (atoms / metal) has been oxidised
- Oxidation is the loss of electrons
- Silver (ions) have been reduced
- Reduction is the gain of electrons
- Both oxidation and reduction occur simultaneously / this reaction is a redox reaction
Key terms in this question
oxidation · reduction · electron transfer
Related
- All Eduqas A-Level Chemistry revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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