During an isothermal expansion, a confined ideal gas does 150 J of work against its surroundings. This implies that:
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Question

During an isothermal expansion, a confined ideal gas does 150 J of work against its surroundings. This implies that:

G1 Physics · Accepted Answer

Step 1: For an ideal gas, internal energy depends only on temperature. Step 2: The expansion is isothermal, so ΔT = 0 and consequently ΔU = 0. Step 3: The gas does positive work: W = +150 J. Step 4: From the first law Q = ΔU + W = 0 + 150 = +150 J. Step 5: Positive Q means the gas absorbs heat from its surroundings to maintain constant temperature while doing work. Final answer: (D) 150 J of heat added.