Equal volumes of sugar water and distilled water is in the same cup. Which solution will evaporate faster?
Vapor pressure lowering of the solution
When sugar (non-volatile solute) dissolves in water, a strong attraction acts between the sugar molecules and the water molecules. Therefore, the higher the concentration, the more difficult for the water to evaporate. Besides, sugar molecules do not evaporate but rather arrange on the solution's surface, reducing the surface area to which water molecules can evaporate.
Eventually, the vapor pressure of a solution containing a nonvolatile solute becomes lower than that of a pure solvent.