Phase Changes Extra Practice

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In terms of heat energy a cooling curve is said to be

• exothermic

• endothermic

Answer explanation

A cooling curve represents the change in temperature of a substance as it cools and transitions from a gas to a liquid, or from a liquid to a solid. This process is exothermic, meaning it releases heat energy into the surroundings. Therefore, in terms of heat energy, a cooling curve is said to be exothermic, which is the correct answer to the question.

In terms of heat energy a heating curve is said to be

• exothermic

• endothermic

Answer explanation

A heating curve is said to be endothermic in terms of heat energy. This is because endothermic processes absorb heat energy from their surroundings. In contrast, exothermic processes release heat. Therefore, the correct answer to the question is 'endothermic'.

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