Question

Name an inorganic compound that has the highest lowering of vapour pressure.

Answer 1

Hint: To answer this question we should learn about the phenomenon called lowering of vapour pressure. Lowering of vapour pressure depends upon some factors like Van’t Hoff factor and Concentration of solute.

Complete answer:
Let’s understand what Inorganic compounds are. Inorganic compounds are those chemical compounds in which elements are combined in definite proportions and they do not contain carbon or simply compound that is not organic.
Now, we discuss vapour pressure. When we add a solute to the liquid or pure solvent the surface of the liquid now contains both solute particles and solvent particles. This reduces the amount of solvent molecule that was initially escaping through the vapour which in turn reduces the pressure exerted by vapour on the liquid this is known as Relative lowering in vapour pressure. It is a colligative property that depends upon the concentration of solute molecules or ions.
Lowering of vapour pressure depends upon several factors
The Concentration of solute: Higher the concentration of solute higher will be lowering in vapour pressure.
Van't Hoff factor: Higher will be the Van't Hoff factor higher will be the lowering in vapour pressure.
Now concentration is a common property for any solute but the Van't Hoff factor is different for most solutes. The inorganic compound which has the highest value of Van't Hoff factor will have the highest lowering in vapour pressure.
Barium chloride on dissociation gives one mole of Barium ions and two moles of Chloride ions So Van’t Hoff factor for Barium chloride will be three and it will have the highest lowering in vapour pressure among inorganic compounds.

Note:
The Van't Hoff factor can be calculated by the total number of moles of ions formed on the dissociation of the compound. It can also be calculated from the dissociation constant and the number of ions formed from one formula unit of the compound.