The release of energy can be used to provide heat when a fuel burns in a furnace, to
produce mechanical work when a fuel burns in an engine, and to generate electrical
work when a chemical reaction pumps electrons through a circuit. In chemistry, we
encounter reactions that can be harnessed to provide heat and work, reactions that
liberate energy that is released unused but which give products we require, and reactions
that constitute the processes of life. Thermodynamics, the study of the transformations
of energy, enables us to discuss all these matters quantitatively and to make
useful predictions.