Determination of enthalpy of mixing

When two substances A and B are mixed together without initiating a chemical reaction, heats of mixing are released or consumed. If the mixing process takes place at constant pressure, the heat of mixing is equal to the enthalpy of mixing.
The cause of the enthalpy of mixing lies in the differences of the interaction energies of the similar molecules in the pure components along with the interaction energy between the different types of molecules in the mixture. If the interaction between similar molecules is stronger than between dissimilar ones, the mixing requires energy, so the solution cools down. In the opposite case, the solution warms up.
Experiment C4.3.3.4 determines the enthalpy of mixing of two solutions with different concentrations and measures the heat of mixing released.