Question

1 mole of ideal gas at 270C is expanded isothermally from an initial pressure of 3 atm to afinal pressure of 1 atm in two ways: (a) reversibly and (b) against a constant external pressure of 1 atm. Calculate q, w, ΔU, ΔH and ΔS for each path.

Answer 1

The temperature is constant in an isothermal process

a)

b) For an isothermal process either reversible or irreversible the internal energy change, delta U is equal to zero (U=0)

c) From the first law of thermodynamics, U=Q+W

Q = -W =

d)

e)