23
QuizMultiple Choice

Unit Test — Unit test

Question 23 • ECTC-AL-Chemistry B

How is the kinetic energy of the particles of a substance affected during a phase change?

Answer
A
Kinetic energy increases during exothermic changes and decreases during endothermic changes.
B
Kinetic energy decreases during exothermic changes and increases during endothermic changes.
C
Kinetic energy does not change, but the potential energy does.
D
Kinetic energy changes in the opposite way that the potential energy changes.

Explanation

During a phase change, the substance’s temperature remains constant. Because average particle kinetic energy depends on temperature, kinetic energy does not change; energy instead changes the particles’ potential energy as they rearrange or separate. Therefore, the correct choice is “Kinetic energy does not change, but the potential energy does.”

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