- #1
grangr
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Homework Statement
Which of the following statement(s) is (are) correct when an ideal gas goes from an initial to a final state in a single process?
a. No work is done on or by the gas when the volume remains constant.
b. No energy is transferred into or out of the gas as heat transfer when the temperature remains constant.
c. The internal energy of the gas does not change when the pressure remains constant.
d. All the statements above are correct.
e. Only statements (a) and (b) above are correct.
b. No energy is transferred into or out of the gas as heat transfer when the temperature remains constant.
c. The internal energy of the gas does not change when the pressure remains constant.
d. All the statements above are correct.
e. Only statements (a) and (b) above are correct.
Homework Equations
- ΔH = ΔE + Δ(PV) = Q + W + Δ(PV), and for ideal gas, ΔH = nCvΔT + Δ(nRT) = nCvΔT + nRΔT = nCpΔT
The Attempt at a Solution
The answer given is (a), while my attempt was (e). I do not understand why (b) is incorrect.
a. Given constant V, ΔV = 0, thus W = 0. (a) is correct.
b. Given constant T on ideal gas, ΔE (or ΔU, internal energy) = 0, thus there is no energy transferred as heat in or out of the system. But why is (b) incorrect then?
c. Given constant P, ΔP = 0, therefore W = - PΔV. Thus ΔH = Q - PΔV + P(ΔV) = Qp. As there might be heat exchange, (c) may or may not hold.
Thank you for your help.