Question

When an acid is slowly added to water:
A.It releases heat
B.It absorbs heat
C.There is no heat change
D.None of these

Answer 1

Hint:When strong acid is mixed with water, a large amount of heat is released. If we added more acid, then more heat would be released. Now add water in acid, it forms an extremely concentrated solution which boils very violently and acid splashing out of the container. If we add acid in water, the solution becomes diluted and a very small amount of heat is released, which is not enough for vaporization.

Complete step by step answer:
When we add acid to water, the solution forms dilute and the heat released in a very small amount which is not enough for the process of vaporization. If this process is done in reverse, it is not possible.
If we add water to acid, it forms a concentrated solution which releases heat. That solution may boil and splash concentrated acid out of the container. All this reaction is called an exothermic reaction which is safer to add acid to water, not water to acid.
As we see what happens if we add water to acid and acid to water, we conclude that adding acid to water is a very safe reaction and at the end of reaction, it releases heat.
Hence, Option (A) is the correct answer.

Note:When acid reacts with water, it releases protons rapidly and forms ions, which are more stable and forms with hydrogen bonding. As a result of reaction, energy releases and releases heat also. When we add water to acid, acid is added in large amounts but very huge molecules get protonated and release too much heat which gets acid boils and contact with acid and burns the skin.