For a salt to disoolve in water , its hydration enthalpy shud be greater than its lattice enthalpy But what if hydration enthalpy is equal to lattice enthalpy?? Will the salt dissolve or not??

Dear Ranjita,

(i) ionic compound(s) + aq  cations(aq)  +  anions(aq)
(ii) solid ionic compound vapourised to give gaseous ions - this ΔH is called the LATTICE ENTHALPY	(endothermic)	gaseous cations and anions	(exothermic)	(iii) hydration of the cations and anions - theseΔHs are called the ENTHALPY of HYDRATION of the ION
In terms of enthalpy changes: (i) = (ii) + (iii) Enthalpy of solution ΔHsolution(compound) is defined as the heat absorbed or released when 1 mole of compound dissolves in water Lattice enthalpy ΔHLE(compound) is defined as the energy released when 1 mole of a solid is formed from its separated gaseous ions Enthalpy of hydration is defined as the energy released when 1 mole of gaseous ions interacts with water to give a solution of the hydrated ions All three enthalpy terms are re-defined in more detail and explained in further detail as  the discussion proceeds.

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