Name the type of chemical reaction in which calcium oxide reacts with water. Justify your answer by giving balanced chemical equation for the chemical reaction.
Generated by claude-sonnet-4-6 · 2026-06-14 10:28 · grounding rag
Model Answer
The reaction between calcium oxide and water is a combination reaction (also exothermic).
Justification: Two reactants (CaO and H₂O) combine to form a single product (calcium hydroxide). A reaction in which two or more substances combine to form a single product is called a combination reaction.
Balanced chemical equation:
$$\text{CaO}(s) + \text{H}_2\text{O}(l) \rightarrow \text{Ca(OH)}_2(aq) + \text{Heat}$$
Source: Chapter 1, Section 1.2.1 Combination Reaction
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Explanation
- 1 mark for correctly naming the reaction type (combination reaction).
- 1 mark for the balanced equation with correct formulae and state symbols.
- Always write state symbols — (s), (l), (aq) — as they show you understand the reaction fully.
- You may also mention it is exothermic (heat is released), but the primary answer required is "combination reaction."