Question

Xamine the graph. Select the statement that best describes the energy change in the particles of a substance during melting.

Answer 1

Answer:

• Option B) Absorbed energy results in the change in potential energy.

Explanation:

Please, find attached the graph that accompanies this question.

The melting proces is the change from solid phase to liquid phase. It is represented with the lower flat line with the symbol ΔHfus over it.

The line is flat because the temperature remains constant during this process. Thus, you know the option "C) As the temperature increases during melting, the kinetic energy also increases" is FALSE.

What happens during this process is:

• Most of the energy received by the particles from heating, during the melting process, goes to overcome the intermolecular bonds between the particles. This results in increasing the distance between the particles, so the internal potential energy increases. This is what the option "B) Absorbed energy results in the change in potential energy" correctly describes. Hence, option B) is TRUE.

Althoug most of the heat energy received is transformed into potential energy, yet a small part of the heat energy increases a bit the kinetic energy of the particles, because the particles will vibrate faster around their relatively fixed positions. Hence, the option "A) The kinetic energy of the particles remains unchanged" is FALSE.

As for option D) it is not reasonable at all: none chemical or physical priciple can be used to state that the kinetic energy decreases as the particles move farther apart. Thus, this is FALSE.