CH353 - Physical Chemistry I
Spring 2012, Unique 52135

Lecture Summary, 1 February 2012

A Bit More on Paths:  The last important pathway we will talk about is when q = 0.  This is called an adiabatic path.  By setting deltaU = w, we derived the following equation:

   Cv/nR ln (Tf/Ti) = ln (Vi/Vf)

We then manipulated this equation further to put it in a form that is easier to solve plug-and-chug style, but this is the important result.

Thermochemistry:  We then went on and discussed the topic of thermochemistry, the science of the flow of heat due to chemical transformations:

   Reactant --> Product +/- heat

In chemical thermodynamics we almost always are interested in energies at constant pressure, therefore in reaction enthalpies of a system.  Because enthalpy is a state function, by defining a standard state of P = 1 bar and T = 298 K, we can tabulate enthalpies of formation for any substance under that standard, then use that information to calculate a reaction enthalpy under any set of circumstances, even those far away from the standard state.