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Chapter 11: Problem 41

(a) What phase change is represented by the "heat of fusion" of a substance? (b) Is the heat of fusion endothermic or exothermic? (c) If you compare a substance's heat of fusion to its heat of vaporization, which one is generally larger?

Short Answer

Expert verified
(a) The phase change represented by the "heat of fusion" is the transition of a substance from the solid phase to the liquid phase at its melting point, keeping the temperature constant. (b) The heat of fusion is an endothermic process, as it requires the addition of heat energy for the phase change to occur. (c) Generally, a substance's heat of vaporization is larger than its heat of fusion, as more energy is needed to overcome the intermolecular forces in the transition from liquid to gaseous phase than from solid to liquid phase.

Step by step solution

01

Define heat of fusion

The heat of fusion is the amount of heat energy required to change a substance from the solid phase to the liquid phase at its melting point, while keeping the temperature constant.
02

Determine if the heat of fusion is endothermic or exothermic

The heat of fusion is an endothermic process because it requires the addition of heat energy to the substance in order to change its phase from solid to liquid. As heat energy is absorbed by the substance, its molecules gain energy and break the bonds holding them together in the solid phase, allowing them to move more freely and form the liquid phase.
03

Compare heat of fusion to heat of vaporization

The heat of vaporization is the amount of heat energy required to change a substance from the liquid phase to the gaseous phase at its boiling point, while keeping the temperature constant. In general, the heat of vaporization is larger than the heat of fusion for a substance. This is because it requires more energy to overcome the intermolecular forces between the molecules and allow the molecules to move completely unrestricted in the gaseous phase, compared to the energy needed to overcome the forces holding the molecules together in the solid phase and allow them to move more freely in the liquid phase.

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Most popular questions from this chapter

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