For the isothermal (constant-temperature)expansion of an ideal gas, A)w 0 and q 0. C)w 0 and q 0.

Question

For the isothermal (constant-temperature)expansion of an ideal gas, A)w > 0 and q < 0. B)w = 0 and q > 0. C)w < 0 and q = 0. D)w < 0 and q > 0. E)w > 0 and q > 0.

Quizplus · Accepted Answer

In an isothermal expansion, the temperature remains constant. As the gas expands, it does work on the surroundings, so w (work) is negative. However, since the temperature is constant, there is no change in internal energy, so ΔU = q + w = 0. This means that q (heat) must have the opposite sign of w, so q > 0 for an exothermic process. Therefore, the correct choice is D.

For the Isothermal (Constant-Temperature)expansion of an Ideal Gas