Thermochemistry

The word thermodynamics is derived from the Greek words that mean "heat" and "power." Thermodynamics is studied and has applications in all the sciences. Thermochemistry is the part of thermodynamics that studies the relationship between heat and chemical reactions. Thermochemistry is a very important field of study because it helps to determine if a particular reaction will occur and if it will release or absorb energy as it occurs. It is also possible to calculate how much energy a reaction will release or absorb and this information can be used to determine if it is economically viable to use a particular chemical process. Thermochemistry, however, does not predict how fast a reaction will occur.

In order to understand the terminology of thermochemistry it is first necessary to define the world as viewed by thermodynamics. The chemical reaction being studied is considered to be the "system." For instance, if an acid is being mixed with a base, the acid, the base, any water used to dissolve them and the beaker in which they are all held are considered the system. Everything else that is not part of the system is considered to be the "surroundings." This includes everything from the countertop on which the beaker is held to the planets in outer space. The system and surroundings together form the "universe." From this wide set of definitions, it is easy to understand why the system is the only part of any interest to us. The surroundings are too complex to be considered.