Propositions For a reversible cycle, absorbing q, atT and g2 at T2, the ratio q: q2 depends only on Tand t2 2. This ratio may be written: q q2=t,/ T2 3. Th he entropy, S, defined by ds=(dq/t) rev S a function of state 4. In an isolated system, As is zero for a reversible process, and positive for a spontaneous one Chemistry 331
Chemistry 331 Propositions 1. For a reversible cycle, absorbing q1 at T1 and q2 at T2 , the ratio q1 :q2 depends only on T1 and T2 . 2. This ratio may be written: q1 /q2 = T1 /T2 3. The entropy, S, defined by dS=(dq/T)rev is a function of state. 4. In an isolated system, DS is zero for a reversible process, and positive for a spontaneous one
The Entropy function The entropy s is defined by reversible state B y ds= dg/t' ds-dqre T dS≠ dqirrey/ irreversible 4S≠d/T state A Chemistry 331
Chemistry 331 • The entropy S is defined by dS = dqrev/T • dS dqirrev/T The Entropy Function reversible: dS = dq/T irreversible: dS dq/T state A state B
The Second Law(clausius) The entropy s is a function of state ds >dq / T(clausius inequality o ds= dq /t for a reversible change o ds> dg/t for an irreversible change Corollary For an isolated system ds=0 for a reversible change ds>o for an irreversible change Chemistry 331
Chemistry 331 The Second Law (Clausius) • The entropy S is a function of state. • dS dq / T (Clausius inequality) • dS = dq / T for a reversible change • dS > dq / T for an irreversible change • Corollary: For an isolated system • dS = 0 for a reversible change • dS > 0 for an irreversible change