(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?

Verified step by step guidance

1. Step 1: Understand the term 'heat of fusion'. The heat of fusion refers to the amount of energy required to change a substance from the solid phase to the liquid phase at its melting point, without changing its temperature.
2. Step 2: Determine whether the heat of fusion is endothermic or exothermic. Consider that during the melting process, energy is absorbed by the substance to overcome the forces holding the solid together, indicating an endothermic process.
3. Step 3: Compare the heat of fusion to the heat of vaporization. The heat of vaporization is the energy required to change a substance from the liquid phase to the gas phase at its boiling point. This process generally requires more energy than melting because it involves completely breaking the intermolecular forces.
4. Step 4: Conclude that the heat of vaporization is generally larger than the heat of fusion. This is because vaporization requires overcoming all intermolecular forces to transition to a gas, whereas fusion only requires enough energy to allow molecules to move past each other in the liquid state.
5. Step 5: Summarize the concepts: (a) Heat of fusion involves the solid to liquid phase change, (b) it is an endothermic process, and (c) the heat of vaporization is typically larger than the heat of fusion due to the greater energy needed to transition to a gaseous state.