Question

why dissolution of some solid compounds is exothermic while that of some other is endothermic

Answer 1

Because of their different reactivity

Answer 2

Hii buddy,

● Why dissolution of some solid compounds is exothermic while that of some other is endothermic ?
- When we dissolve a solid in water, its components dissociate (which requires energy) and bond with water molecules (which releases energy).
- When energy required to separate constituents of solid is more than that of energy released by bonding with water molecules, temperature is decreased. This reaction is called endothermic reaction.
- When energy required to separate constituents of solid is less than that of energy released by bonding with water molecules, temperature is increased. This reaction is called exothermic reaction.

Hope this helps you...