Thermochemistry is an extremely useful application of thermodynamics because it allows us to use previously gathered data to estimate the enthalpy changes of processes that we have not yet done, or th...Thermochemistry is an extremely useful application of thermodynamics because it allows us to use previously gathered data to estimate the enthalpy changes of processes that we have not yet done, or that are unknown to us. The two most common applications are the use of Hess's Law to combine the enthalpy changes of entire chemical equations, and the combination of the enthalpy changes of formation of the pure substances involved in a process.
