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The heat released or consumed duńng particular Chemical reaction can be measured calorimetrically. There are two distinct techniąues iised: a constant volume calorimetry and tlie constant pressnre calorimetry. The former one is nsed to detennine intemal energy change and indii ectly enthalpy change wliile the latter is nsed to detennine enthalpy change directly.

2. Calorimetry

Constant voluine calorimetry is of common nse for combnstion or other violent Chemical reaction heat, and indirectly enthalpy detennination:

The reaction takes part into the calorimetric bomb. The increase in water sunounding calorimetric bomb temperaturę is proportional to the heat released. Approx. 1 cal of heat is released (4.184 J) when tlie temperaturę of 1 g of water increases of loC. (1 cal - water heat capacity).

•Constant pressure calorimetric is of common use for non-violent Chemical reaction heat, and entlialpy detennination. In tliis case tlie system doesiTt have to be limited witli a strong bomb walls and simple Styrofoam cups might be applied.