1. Chapter 17 Notes1 Chapter 17 Thermodynamics: Entropy, Free Energy and Equilibrium 1. review of terms; definitions; 2. Is it spontaneous? 3. entropy; some examples 4. free energy and equilibrium; some examples

2. Chapter 17 Notes2 enthalpy (H): equivalent to the heat that would be transferred during a constant pressure process (hence its usefulness in chemistry); a state function! exothermic: heat released (negative enthalpy change) endothermic: heat absorbed (positive enthalpy change) entropy (S): measure of randomness in a system; measure of the “quality” of energy in a system; a state function. free energy (G): energy available to do chemical work (such as electrochemistry or heating, by combustion) for constant temperature and pressure processes; less than the total energy in the system because the system must pay an entropy tax! A state function.

3. Chapter 17 Notes3 2. Is it spontaneous? Or, Why do certain processes always occur in one direction? mixing of gases (gases don’t separate) expansion of gases (gases don’t contract) thermal equilibration (if you leave the refrigerator open, it warms up!) ice melts at or above 0°C water boils at or above 100°C chemical cold packs combustion of hydrogen

4. Chapter 17 Notes4 What do these examples have in common? Net Gain in Entropy for System + Surroundings system entropy,  S, increases due to mixing, increased molecular motion, smaller molecules, less structured molecules surroundings entropy,  H/T, increases due to T increase from an exothermic reaction - surroundings’ randomness increases