When an ideal gas is compressed isothermally
A) the internal energy of the gas does not change.
B) the work done on the gas is zero.
C) heat flows into the gas.
D) the temperature of the gas increases.

Question

Quizplus · Accepted Answer

Isothermal compression means that the temperature of the gas remains constant. Therefore, by the first law of thermodynamics, the change in internal energy (ΔU) of the gas is zero. As work is done on the gas during the compression, according to the work-energy principle, the heat entering the gas is negative heat of compression. Therefore, choice A is correct. Choices B and C are incorrect. As the temperature of the gas remains the same during the compression, choice D is also incorrect.

When an Ideal Gas Is Compressed Isothermally