Question

Give reason for during preparation of dilute sulphuric acid , concentrated sulphuric acid should be added into water but the reverse is not true.

Answer 1

First, adding more acid releases more heat, as it is exothermic. If you add water to acid it forms an extremely concentrated solution of acid initially. So much heat is released that the solution may boil very violently, splashing concentrated acid out of the container and all this because the reaction is exothermic.