SL: Entropy and Spontaneity/Equilibrium

Entropy and Spontaneity/Equilibrium

Positive Entropy change of the universe $\to$ spontaneous process

For equilibrium: $dS_{univ} \to $ "maximum"

$dS_{univ} = dS_{sys} + dS_{surr} = dS_{sys} + \frac{\delta Q_{surr}}{T_{surr}} = dS_{sys} - \frac{\delta Q_{sys}}{T_{surr}} \ge 0$