Stoichiometry - Engineering

Q1:

Addition of a non-volatile solute to a pure solvent

A increases its freezing point.

B increases its boiling point.

C decreases its freezing point.

D both (b) and (c)

ANS:D - both (b) and (c)

The correct answer is: both (b) and (c). When a non-volatile solute is added to a pure solvent:

  1. Freezing Point: The presence of the solute disrupts the formation of the solvent's crystal lattice, so it takes a lower temperature to freeze the solution than it would to freeze the pure solvent. Hence, the freezing point decreases.
  2. Boiling Point: The addition of a non-volatile solute elevates the boiling point of the solvent. This happens because the vapor pressure of the solution is lowered compared to that of the pure solvent, requiring a higher temperature for the solution to reach its boiling point.
So, adding a non-volatile solute to a pure solvent affects both the freezing point and the boiling point.