Question
Tue January 08, 2013 By:

can you please explain effect of temperature on solubilty and how endothermic and exothermic processes affect solubility?

Expert Reply
Tue January 08, 2013
The solubility of solutes is dependent on temperature. When a solid dissolves in a liquid, a change in the physical state of the solid analogous to melting takes place. Heat is required to break the bonds holding the molecules in the solid together. At the same time, heat is given off during the formation of new solute -- solvent bonds.
An increase in temperature contributes to a decline in the solubility of gases in water, water that is of a higher temperature lacks oxygen.
  1. Exothermic reaction:If the heat given off in the dissolving process is greater than the heat required to break apart the solid, the net dissolving reaction is exothermic (energy given off). The addition of more heat (increases temperature) inhibits the dissolving reaction since excess heat is already being produced by the reaction.
  2. Endothermic reaction:If the heat given off in the dissolving reaction is less than the heat required to break apart the solid, the net dissolving reaction is endothermic (energy required). The addition of more heat facilitates the dissolving reaction by providing energy to break bonds in the solid. This is the most common situation where an increase in temperature produces an increase in solubility for solids.
Ask the Expert