Michael Blaber, PhD
Florida State University: Thermochemistry: Hess's Law
This article from the Florida State University provides an excellent explanation of WHY Hess's Law works and examples of how to use the law. Common mistakes are identified and explained.
Other
Austin Community College: Handout on Enthalpy
A step-by-step example of how to complete Hess's Law problems. This example includes all the manipulations that may be required for Hess's Law.
University of Sydney (Australia)
Entropy and the Second Law of Thermodynamics [Pdf]
A set of printable pdf pages from the University of Sydney's "Thermal Physics Module" site. Entropy is defined and explained conceptually. The mathematical treatment of entropy is introduced. The second law of thermodynamics and its...