We can calculate the value of the standard state enthalpy change, Ho, and the standard state entropy change, So, for a chemical change from measurements of the equilibrium constant for the change at several different temperatures.
Calculating Enthalpy Changes and Entropy Changes from the Change in Keq with Temperature
To determine Ho and So, plot ln Keq vs 1/T. The resulting straight line will have a slope equal to -Ho/R and an intercept equal to So/R.
The derivation for this relationship follows:
|We have seen that|
|Thus we can write|
This last equation is the equation of a straight line with a a slope of -Ho/R and an intercept equal to So/R.