Question

A solution X is prepared by dissolving three moles of glucose in one litre of water and a solution Y is prepared by dissolving 1.5 moles of sodium chloride in one litre of water. Will the osmotic pressure of X be higher, lower or equal to that of Y? Give a reason for your answer.

Answer 1

The osmotic pressure of X will be equal to that of Y.

Reason: Osmotic pressure is a colligative property. Its value depends upon the number of particles of solute present in the solution. 3 moles of glucose gives 3 moles of molecules (particles) in solution. 1.5 moles of NaCl, due to complete dissociation provides 3 moles of ions (particles) in solution. Molar concentrations of solutions are the same and their osmotic pressures are also equal.