When a volatile solute is added to a solution, how does it affect the overall pressure of the vapor?

When a volatile solute is added to a solution, the overall vapor pressure increases due to the contribution of the vapor pressure of the solute itself. A volatile solute is one that has a significant vapor pressure and can evaporate into the gas phase.

In a solution, the presence of the volatile solute introduces additional molecules that can escape into the vapor phase, thereby increasing the total number of gas-phase particles above the liquid. According to Raoult's Law, the vapor pressure of a solution containing a volatile solute is equal to the sum of the partial pressures of the components in the solution. Since both the solvent and the solute contribute to the overall pressure, adding a volatile solute with its own vapor pressure leads to an increase in the total vapor pressure above the solution.

This principle highlights the importance of understanding the relationship between solute and solvent vapor pressures in a solution, demonstrating that the addition of a volatile substance directly influences the equilibrium between liquid and gas phases, resulting in a higher overall pressure of the vapor.