why beryllium sulphate and magnesium sulphate soluble in water,while calcium sulphate is not?
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Solution
As the size of cation increases, solubility decreases.
Two factors are involved in dissolving:
Lattice energy
Enthalpy of hydration.
Be2+ and Mg2+ are the smallest cations of group 2 elements, thus having highest hydration enthalpy. Thus, their sulphates are soluble. However, Ca2+ is larger in size, so it has least hydration enthalpy. Thus CaSOā4 is insoluble.