Calorimetry

Calorimetry is defined as the science of measurement of energy changes in the form of heat; the apparatus in which this change is measured is called a calorimeter. Calorimetric techniques measure the enthalpy or heat of a reaction, changes in heat content of a substance associated with changes in temperatures, changes of state such as melting and boiling, changes of chemical combination such as reactions, or alloying, or dissolution. The changes of physical structure like heat of order-disorder transformation, and energy stored in cold working can also be measured by alloy solution calorimetry by the alternate dissolution of ordered and disordered and annealed and cold worked samples, respectively. The successful and versatile use of the calorimetric technique in thermodynamic measurements has encouraged the development of various types of calorimeters. Calorimeters have been classified into five main groups viz. isothermal, adiabatic, isoperibol, constant temperature gradient, and variable temperature gradient on the basis of the simplified heat flux eq. A brief discussion has been included on twin micro-calorimeter along with principle and application of these five types of calorimeters.