Thermochemistry

Thermochemistry is the study of the heat energy which is associated with chemical reactions and/or phase changes such as melting and boiling.

Thermochemistry focuses on the energy exchange between a system and its surroundings in the form of heat.

In combination with entropy determinations, it is also used to predict whether a reaction is spontaneous or non-spontaneous, favorable or unfavorable.

Stated in modern terms, they are as follows:[1] These statements preceded the first law of thermodynamics (1845) and helped in its formulation.

An isobaric (same-pressure) process occurs when the pressure of the system remains constant.

The world's first ice-calorimeter , used in the winter of 1782–83, by Antoine Lavoisier and Pierre-Simon Laplace , to determine the heat evolved in various chemical changes ; calculations which were based on Joseph Black 's prior discovery of latent heat . These experiments mark the foundation of thermochemistry .