Generated by claude-sonnet-4-6 · 2026-06-14 10:30 · grounding rag
Model Answer
Product: Copper oxide (CuO)
Colour: Black
Chemical Equation:
$$2\text{Cu}(s) + \text{O}_2(g) \xrightarrow{\Delta} 2\text{CuO}(s)$$
When copper is heated in air, it reacts with oxygen to form copper(II) oxide, which is black in colour. This is an oxidation reaction.
Source: Chemical Reactions and Equations, Chapter 1 (also referenced in Exercise Q.17)
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Explanation
- This question is directly linked to Exercise Q.17 of Chapter 1, where element 'X' (shiny brown = copper) turns black on heating — the black compound is CuO.
- Must include: name of product, colour (black), and balanced equation — one mark each.
- Write the balanced equation correctly: 2Cu + O₂ → 2CuO (coefficients are essential for full marks).
- Mentioning it is an oxidation/combination reaction adds value but is not strictly required for 2 marks.