A chemical company in Brazil uses self-heating cans for coffee. The can contains two compartments separated by a membrane. When the membrane is broken, calcium oxide reacts with water.

CaO + H₂O → Ca(OH)₂

Why does this reaction heat the coffee?

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Question

A chemical company in Brazil uses self-heating cans for coffee. The can contains two compartments separated by a membrane. When the membrane is broken, calcium oxide reacts with water.

CaO + H₂O → Ca(OH)₂

Why does this reaction heat the coffee?

Accepted Answer

The reaction is exothermic and releases heat to the coffee — Award 1 mark for identifying the reaction as exothermic with energy transfer to surroundings. A is incorrect — endothermic reactions would cool the coffee. C is incorrect — this confuses product properties with energy release. D is incorrect — the water reacts rather than evaporates.

Answer

The reaction is exothermic and releases heat to the coffee

Answer

The calcium hydroxide produced has a higher temperature than the reactants

Answer

The reaction is endothermic and absorbs heat from the coffee

Answer

The water evaporates and transfers heat to the coffee

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