Example of Calculating Equilibrium Constant Using Mean Heat Capacities and Standard Entropies

This example shows how to calculate the equilibrium constant for a reaction using mean heat capacities and standard entropies. The reaction in question is the dissociation of water vapor into hydrogen and oxygen gases. The calculation is done at 2000 degrees Celsius and 0.01 bar.

Questions

1. What is the standard enthalpy of formation of H2O?
2. What are the standard entropies of H2O, H2, and O2?
3. What are the mean heat capacities of H2O, H2, and O2?

Answers

1. The standard enthalpy of formation of H2O is -241.8 kJ/mol.
2. The standard entropies of H2O, H2, and O2 are 188.3, 130.7, and 205.1 J/mol K, respectively.
3. The mean heat capacities of H2O, H2, and O2 are 33.6, 28.8, and 29.4 J/mol K, respectively.