The branch of chemistry, which deals with the transfer of energy between system and surrounding due to temperature difference, is called Heat Chemistry.
Heat is a form of energy-related to thermal energy transferred between two bodies at different temperatures (therefore, energy in transit).
The unit of measurement of heat is the joule (J), but in chemistry, there is the frequent use of calorie (cal), defined as the amount of heat necessary to raise the temperature of 1 g of distilled water from 14.5 ° C at 15.5 ° C, at a pressure of 1 atm.
Since calorie is a very small unit of measurement, a multiple of it is often used, the kilocalorie (kcal), equivalent to 1000 cal; the calorie, in turn, corresponds to 4.184 J:
The instrument used in particular in chemistry to measure quantities of heat is the calorimeter.
