According to renowned chemist Gilbert Lewis "Physical chemistry is anything interesting." As a combined science of physics, chemistry, thermodynamics, electrochemistry, and quantum mechanics it functions to provide molecular-level interpretations of observed macroscopic phenomena. Typically, changes in temperature, pressure, volume, heat, and work of systems in the solid, liquid, and or gas phase are correlated to microscopic atomic and molecular interactions.
The type of relationships that physical chemistry tries to resolve include:
How the identity of ions affects electrical conductivity of materials
Most cite Willard Gibbs as the founder of physical chemistry as stemming from his 1876 paper: “On the Equilibrium of Heterogeneous Substances”, wherein such cornerstones as free energy, chemical potential, and phase rule were developed.
