Question

question 9
why does adding a non - volatile solute change the boiling point of a solution?
the solution needs a higher temperature to dissolve the solute completely.
the solution needs a lower temperature to lower its entropy.
the solution needs a higher temperature to match its vapor pressure with atmospheric pressure.
the kinetic energy of solute molecules is transferred to solvent molecules, which heats the solution.

Explanation:

The boiling point of a liquid is the temperature at which its vapor pressure equals the atmospheric pressure. When a non - volatile solute is added to a solvent, the vapor pressure of the solution is lower than that of the pure solvent. So, a higher temperature is required for the vapor pressure of the solution to match the atmospheric pressure, thus increasing the boiling point.

Answer:

The solution needs a higher temperature to match its vapor pressure with atmospheric pressure.