This chapter will explain the origin of the spontaneity of physical and chemical change. Two simple processes are examined. It shows that a property, the entropy can be defined, measured, and used to discuss spontaneous changes quantitatively. This chapter also introduces a major subsidiary thermodynamic property, the Gibbs energy

The First Law: the machinery In this chapter we begin to unfold some of the power of thermodynamics by showing how to establish relations between different properties of a system. The procedure we use is based on the experimental fact that the internal energy and the enthalpy are state functions. and we derive a number of relations between observables by exploring the mathematical consequences of these facts