Simple Definitions of a Few Thermodynamic Concepts

Lightly paraphrased from Dan Schroeder's ``The Undergraduate Thermal Physics Course: Who Should Take it and Why?''

Regarding clarity of presentation, I don't think there are any magic prescriptions, but please remember that concepts such as entropy and enthalpy and free energy and chemical potential can be explained in clear, vivid English.

• Entropy is the logarithm of the number of ways of arranging things.
• Enthalpy is the energy of the system plus the work you need to do to make room for it.
• Free Energy is the work you can extract by annihilating the system, not including any heat that you must dump into the environment to get rid of the system's entropy.
• Temperature is a measure of the tendency of a system to give up energy, just as
• Pressure measures its tendency to expand, and
• Chemical Potential measures its tendency to give up particles.
• Even the Partition Function, that most abstract of thermodynamic quantities, is more or less just the number of states accessible to a system when it's held at constant temperature.

None of these verbal interpretations is particularly hard to remember, yet all too often, they tend to get buried in the mathematics.