Question

Which of the following generalizations cannot be made about the phase change of a pure substance from solid to liquid?
A. It involves a change in potential energy
B. It involves no change in temperature
C. It involves a change in kinetic energy
D. It involves change in entropy
E. It may occur at different temperatures for different compounds

Answer 1

Hint: We are asked to state the wrong one from the options given. This question is based on the concept of phase change. We can start to attempt this question by defining phase change and how it occurs. This will lead us to our required solution.

Complete answer:
In thermodynamics, phase change or phase transition is the process by which matter changes its state of matter from one to another. These are mainly three states of matter as of now. Solid, liquid and gaseous state.Phase transition or phase change usually occurs when the temperature is changed to a particular level. Basically, it involves the addition of heat energy or the removal of it. This causes the temperature to change.

The entropy increases if the phase transition is towards the phase having higher internal energy, for instance melting. When heat is added to the system, the potential energy increases and when heat is removed, the potential energy is released. When the temperature is increased, there involves very little or negligible change in kinetic energy as the particles only vibrate in their place.

Hence, the correct answer is option C.

Note: During the transition from one phase to another, the temperature is brought to one particular level. However, during the transition of one phase, the temperature does not change until all of the matter is turned or transitioned to the other phase. This can cause confusion between the second and third option, but keeping the fact in mind helps to avoid that confusion.