While preparing dilute sulphuric acid, concentrated H_2SO_4 must always be added slowly to water (and never the reverse) because

JEE Main Chemistry question

While preparing dilute sulphuric acid, concentrated must always be added slowly to water (and never the reverse) because

(A)Water is denser than the acid, so it would not mix otherwise
(B)Hydration of is strongly exothermic, and adding acid to the larger volume of water lets that heat dissipate safely, instead of causing localized boiling and violent spattering of acidCorrect
(C)Acid reacts explosively with glass if water is added to it first
(D)Water decomposes concentrated if added directly to it

Answer: (B)

Solution

Dissolving/hydrating concentrated in water is a highly exothermic process. Adding acid gradually, in a thin stream, to a large volume of water allows the heat released to be absorbed and dissipated throughout the water. Doing the reverse — adding

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Question ID VK-145924