Entropy Change Associated with Phase Changes

This text discusses the entropy change associated with phase changes. It provides formulas for calculating the entropy change for melting, heating, and vaporizing a substance, as well as for changing the state of a perfect gas. It also discusses the difference between reversible and irreversible phase changes.

Questions

• What is the melting point of water?
• What is the entropy change for the melting of two moles of water if the heat of fusion is 6 kJ/mol?
• What is the entropy change for heating a mole of water from 0°C to 100°C at constant pressure?
• What is the entropy change for vaporizing a mole of water at 100°C and 1 atm?
• What is the difference between reversible and irreversible phase changes?

Answers

• The melting point of water is 0°C.
• The entropy change for the melting of two moles of water if the heat of fusion is 6 kJ/mol is 0.044 kJ/K.
• The entropy change for heating a mole of water from 0°C to 100°C at constant pressure is 1.23 kJ/K.
• The entropy change for vaporizing a mole of water at 100°C and 1 atm is 75.3 kJ/K.
• The difference between reversible and irreversible phase changes is that a reversible phase change can be reversed, while an irreversible phase change cannot.