Enthalpy and Entropy Changes in an Ideal Gas

This blog post discusses the enthalpy and entropy changes that occur when an ideal gas undergoes two reversible processes: an isothermal expansion and a reversible constant-pressure compression. The enthalpy change of an ideal gas is zero if the temperature doesn’t change, and the entropy change is equal to the heat transferred divided by the temperature.

Questions

• What is the enthalpy change of an ideal gas during an isothermal expansion?
• What is the entropy change of an ideal gas during a reversible constant-pressure compression?

Answers

• The enthalpy change of an ideal gas during an isothermal expansion is zero.
• The entropy change of an ideal gas during a reversible constant-pressure compression is equal to the heat transferred divided by the temperature.