Question

Sulphates which are insoluble in water are:
(A) Calcium
(B) Silver
(C) Barium
(D) all of the above

Answer 1

Hint: Salts having anion as sulphate are usually ionic in nature. However not all ionic solids are soluble in water. Solubility depends on the solubility product of the ionic solid. Salts which are insoluble settle down as a precipitate. Insolubility means that the solid cannot expand its lattice to form individual positive and negative ions.

Complete step by step answer:
Solubility is the property of a solid, liquid or gaseous chemical substance also called solute to dissolve in a solid, liquid or gaseous solvent. The solubility of a substance depends mainly on the physical and chemical properties of the solute as well as the solvent.

The factors on which solubility depends are:
- Temperature
- Pressure
- pH of the solution
The extent of the solubility of a substance in a given solvent is measured as the saturation concentration. If we add more solute to this solution, the solute does not increase concentration, instead just precipitates to the bottom of the container or tube.
Insolubility is the inability of the solute to dissolve in the given solvent.
Some ionic compounds dissolve in water due to attraction between positive and negative charges. However, there is a limit to how much salt can be dissolved in a given volume of water.
Sulphates are usually soluble in water as they have a high solubility product. However, there are some exceptions like calcium sulphate, strontium sulphate, barium sulphate, silver sulphate, lead sulphate.
So, the correct answer is “Option D”.

Note: Solubility of an ionic compound can be predicted by the value of its solubility product. Ionic compounds having high value of solubility products are more soluble than ionic compounds having lower value of solubility products.