Question

While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?​

Answer 1

Acid dilution is a highly exothermic process. If water is directly added to an acid, the heat produced would be so great that the acid would splash out and cause damage. Hence it is always recommended to add acid to water in small amounts stirring continously.

Answer 2

Adding water to an extremely concentrated acid generates a lot of heat and as a result, exothermic reaction takes place by which the reaction will 'explode' and is injurious.

Hence, acid is slowly added to water by stirring it and dissolving it so that it has no chance of reacting as vigorously and exothermically as vice versa.