The second law states that the entropy of the universe (system and surroundings) increases in a spontaneous process : delta Ssyst + delta Ssurr is greater than or equal to 0. Argue that, at constant T and p, delta Ssurr is related to the system enthalpy change by delta Ssurr = - delta Hsyst /T. Then argue that delta G is less than or equal to 0 follows, where G is the system Gibbs energy.