Question

Does dissolution or crystallization produce heat?

Answer 1

When we add a substance to a solution then it dissolves in it. The process of dissolving of substance is known as dissolution. Some substances do not dissolve and form crystals inside the solution. The formation of crystals is known as crystallization. In doing both the processes there is involvement of heat as the form of energy.

Complete Answer:
When a substance gets dissolved in the solution then the process is known as dissolution. During the process of dissolution there is breakage of bonds of the solute. The process of breaking the bonds needs some energy. Thus we can say that during the dissolution process we need some energy for breaking bonds. Therefore dissolution is an endothermic process where an amount of heat energy is absorbed. On the other hand when solute is insoluble in water then it forms a crystal within the solution. The process is known as crystallization. During the process of crystallization there is formation of new bonds. Thus some amount of energy is released when there is formation of bonds. Thus we can say that during crystallization an amount of energy is released. Thus crystallization is an exothermic process.

Note:
It must be noted that in an endothermic process the energy is absorbed by the solution while in an exothermic reaction there is release of energy. While exothermic reaction or endothermic reaction, the temperature of solution also changes respectively. Crystallization mainly occurs when anion and cation are attracted towards each other and from crystals respectively. We can conclude that bond formation releases energy while bond breaking needs energy.