Question

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

Answer 1

Hint: An acid is basically defined as a molecule or ion which is capable of donating a proton (basically hydrogen ion ${H^ + }$ ) to another atom or ion . The strength of an acid is judged by how stable it remains after donating hydrogen ions .

Complete step by step answer:
When an acid is added to water, heat is released.
This process is done when we want dilute solutions of concentrated acids.
Greater the amount of acid , more is the amount of heat released.
Now, the question arises as to why only acid is added to water and not water is added to acid?
This is because when we add water to acid , initially the solution is highly concentrated . The process is exothermic and spontaneously so much heat is released that the concentrated acid splashes out of the container.
On the other hand ,when we add acid to water, initially the solution is very dilute.
So the small amount of heat released cannot vaporise it and therefore the solution does not splash out of the container.

So, the correct answer is Option A .

Note:
The above process should be done very slowly and carefully as one deals with concentrated acids. They should be handled with precautions as they are corrosive in nature if an acid comes in direct contact with the skin the skin may get burned .