First law of thermodynamics: When a fixed amount of ideal gas goes through an isothermal expansion,

Question

Quizplus · Accepted Answer

According to the first law of thermodynamics, the change in internal energy (ΔU) of a system is given by the sum of the heat (Q) transferred to or from the system and the work (W) done on or by the system. In an isothermal process, the temperature is constant, so the change in internal energy is zero (ΔU = 0). Therefore, no heat enters or leaves the gas (C) and the gas does work (B) because it expands. The temperature would remain constant (D) as long as the expansion is isothermal. The pressure may or may not increase (E) depending on the specific conditions of the process. Therefore, the best choice is A - the internal (thermal) energy does not change.

First Law of Thermodynamics: When a Fixed Amount of Ideal