What effect does a volatile solute have in a non-ideal solution?

In a non-ideal solution, the presence of a volatile solute affects the vapor pressure in a way that deviates from the ideal behaviors described by Raoult's Law. While Raoult's Law establishes that the vapor pressure of a solvent in a solution is proportional to the mole fraction of the solvent, non-ideality arises when there are strong interactions between the solute and the solvent or when the solute itself is volatile.

When a volatile solute is introduced into a solution, it can contribute to the overall vapor pressure of the solution. The presence of this solute leads to an increase in the total vapor pressure, as the solute molecules can also escape into the vapor phase. This behavior demonstrates that the solution does not strictly adhere to the predictions of Raoult's Law, which assumes ideal behavior and does not account for the interactions and behaviors of mixed phases that are typical in real-world scenarios.

Therefore, the correct description of the behavior of a non-ideal solution containing a volatile solute is that it increases the vapor pressure above the predictions made by Raoult's Law. This reflects the complex interactions at play in such solutions, highlighting the importance of understanding the deviations from ideal behavior in physical chemistry.