Consider 1.0 mole of a monatomic ideal gas in a container fitted with a piston. The initial conditions are 5.0 L and P = 5.0 atm at some constant T.
a. If the external pressure is suddenly changed to 2.0 atm, show that expansion of the gas is spontaneous.
b. If the external pressure suddenly changes back to 5.0 atm, show that compression of the gas is spontaneous.
c. Calculate and compare signs of ΔG for each case (parts a and b) and discuss why this sign cannot be used to predict spontaneity.