We looked at another isolated system where the temperature and pressure can change. Then we considered an open system, where the surroundings come into play as well. This led to the development of a new thermodynamic potential we call Gibbs Free Energy. G is minimized at equilibrium for a system at constant temperature and pressure.

Summary - Slides
Solutions for the first exam from last fall have been posted in the Exams section.

We looked at arbitrary changes in state functions, like entropy, as two variables are changed. This involved using the differential form (dS) and expressing some of the partial derivatives as physically relevant parameters, such as heat capacities, thermal expansion, etc. We also started to look at equilibrium in the case of two isolated bodies in thermal contact.

We also discussed the exam coming up next Friday, October 3.

Summary - Slides

We combined our two laws to form an expression for the internal energy that was a function of the extensive variables S and V. This lead to formal definitions of thermodynamic variables T & P as wells as Maxwell relations. We also introduced H(S,P) which came from our definition of enthalpy. We had a brief discussion about the upcoming exam next Friday, with more details to come later. An old exam from 2007 has been posted online.

Summary - Slides

We finished two of four practice problems involving entropy.

Practice Problems

We took a look at how entropy behaves for a spontaneous versus a non-spontaneous process. We did calculations for reversible and irreversible process involving ideal gases. Also, we began discussing entropy as a function of temperature.

The due date for Homework 4 was moved to Wednesday, September 24.

Summary - Slides

We finished up the practice problems from last time and moved on to begin our discussion the second law. We discussed several statements of the second law and developed the justification for a new state function called entropy.

Summary - Slides - Homework 3 Solutions - Homework 4 - Practice problem 3 solution

We did not cover any new material today in class. We focused on questions from Homework 3 and a series of practice problems involving thermochemistry and enthalpy.

Slides - Practice problems

We discussed the uses for enthalpy when working at constant pressure. We also explored the use of enthalpies of reactions and how to deal with non-standard states.

Summary - Slides - Homework 3

We explored ideal gases and the dependence of U and H on temperature. Two practice problems were completed to illustrate this relationship.

Summary - Slides - Practice Problems

Lecture summary and slides from today’s class. We discussed heat capacity as a way to relate heat transfer to a changed in temperature. Also looked at how to do calculations involving P-V work and an ideal gas. Finally, we introduced the idea of enthalpy.

Summary - Slides - HW #1 Solutions