Question detail
Which of the following half-equations represents the reduction of copper ions?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Oxidation, reduction and redox equations
Question
- A. Cu^2+ + 2e^- → Cu
- B. Cu → Cu^2+ + 2e^-
- C. Cu^2+ → Cu + 2e^-
- D. Cu + 2e^- → Cu^2+
Answer
Cu^2+ + 2e^- → Cu
Explanation
The correct half-equation for the reduction of copper ions shows that copper ions (Cu^2+) gain two electrons (2e^-) to form solid copper (Cu), indicating a decrease in oxidation state.
Common mistake
Identifying Oxidising and Reducing Agents
Students often confuse oxidising agents with reducing agents by not correctly identifying the changes in oxidation states.
To correctly identify oxidising and reducing agents, remember that an oxidising agent is reduced (gains electrons, decreases in oxidation state), while a reducing agent is oxidised (loses electrons, increases in oxidation state). For example, in the reaction where Fe^2+ is oxidised to Fe^3+ and MnO4^- is reduced to Mn^2+, Fe^2+ is the reducing agent and MnO4^- is the oxidising agent. Assign oxidation states to each species before and after the reaction to clarify their roles.
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