Atkins, de Paula & Friedman: Physical Chemistry: Quanta, Matter, and Change 2e
CODATA Key Values of Thermodynamics
Compilation of internationally accepted values for the thermodynamic properties of key chemical substances, proposed by the Committee on Data for Science and Technology (CODATA).
CRC Handbook of Chemistry and Physics
Data may be accessed after purchasing a personal or institutional subscription.
F*A*C*T Thermochemical Database
Very useful database of thermochemical properties that also includes utilities for Gibbs energy minimization calculations.
NIST Chemistry Webbook.
Contains databases of thermochemical properties of a large number of substances.
Classical Thermodynamics: First Law
Brief introduction to the first law.
The First Law of Thermodynamics
Another web page on thermodynamics with some worked examples.
First Law of Thermodynamics
HyperPhysics page on thermodynamics.
Test yourself on Hess's law with this question generator.