Hess's Law problem solving Example 2
Channel: Peter Warburton Chemistry Open Education Resources
Date: 2021-12-02

A second problem solving video on how to calculate the enthalpy change of a reaction of interest when you know enthalpy changes for other reactions with chemicals in common.  This is an application of what is called Hess's Law.  In this case we see that sometimes we need to use one of the step reactions to cancel out chemicals we don't want appearing in the overall reaction after we have followed the same procedure as in the first Example problem.  This Example also starts introducing the idea of step reactions for the formation of compounds from their elements, which leads into the idea of standard enthalpies of formation.