- Physical Chemistry I
Spring 2012, Unique 52135
Lecture Summary, 1 February 2012
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.