Heat is added to an ideal gas and the gas expands. In such a process the temperature
A) must always increase.
B) must always decrease.
C) will remain the same if the work done equals the heat added.
D) will remain the same if the work done is less than the heat added.
E) will remain the same if the work done exceeds the heat added.

Question

Quizplus · Accepted Answer

According to the first law of thermodynamics, in an adiabatic process (no heat exchange), if work is done on the gas, the internal energy (which is directly proportional to the temperature) decreases. Conversely, if work is done by the gas, the internal energy (and temperature) increases. However, in the given scenario, heat is added to the gas and it expands. If the expansion is such that the work done by the gas is equal to the heat added, then there is no change in the internal energy (and temperature) of the gas, and hence the temperature remains constant. Therefore, choice C is the best answer.

Heat Is Added to an Ideal Gas and the Gas