Thermochemistry (20 Min) - heat, pressure, volume, internal energy 

Thermochemistry is the study of changes in heat. Energy transfer calculation is the way to determine how much heat was added to or removed from a system. The system always has a relationship with its surroundings and the sum of them combined equals the universe. The derivation of how heat is calculated is the sum of the change in internal energy and work (a product of the change in volume and constant pressure). By rearranging them in facets of path or state functions, it is possible to designate the heat obtained from the calculation to become a variable we call enthalpy.