Question

Why is the concentrated acid added into water and not water into the acid, while preparing a dilute solution of an acid?

Answer 1

1. Concentrated acid: It has a greater amount of acid per unit volume.
2. Dilute acid: It has a smaller amount of acid and a greater amount of water per unit volume. It is prepared by adding concentrated acid to the water.
3. Dissolution is the process of adding water. And the dissolution of concentrated acid is a highly exothermic reaction (heat-producing).
4. Reason: When even a small amount of water is added to the acid, it produces a huge amount of heat and this heat is enough to boil the acid. This may also spurt the acid and burn the skin of the person. But when a small amount of acid is added to water, then a small amount of heat generated is not enough to vaporize the dilute acid solution, and hence it does not spurt.
5. That is why dilution is done by slowly adding concentrated acid to the water to avoid accidents.