Question

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

Give a reason:

For dilution of an acid, acid is added into water and not water into acid.

Answer 1

The process of dissolving a concentrated acid in water is highly exothermic (releases a large amount of heat).

1. Acid to Water: It is recommended to add acid to water slowly with constant stirring. This allows the large volume of water to absorb the heat evolution safely.
2. Water to Acid: If water is added to concentrated acid, a huge amount of heat is generated instantly. Such reactions can cause the mixture to splash out (spurt) and cause severe acid burns. Additionally, the excessive local heating may cause the glass container to break.