For any solution the partial vapour pressure of each volatile component in the solution is directly proportional to its mole fraction.

Question

1. For any solution the partial vapour pressure of each volatile component in the solution is directly proportional to its mole fraction. Name the law stated above.

2. Study the graph. What phenomenon it denotes? Based on your observation predict the reason for the greater volatility of a mixture of carbon disulphide and acetone?

Answer 1

1. Raoult’s law

2. Positive deviation from Raoult’s law. In a solution formed by adding CS₂ to acetone, the dipolar interactions between solute-solvent molecules are weaker than the respective interactions among the solute-solute and solvent-solvent molecules. Thus, the escaping tendency of the particles increases and the solution shows +ve deviation.