* Vapor Pressure: Volatile substances have a high vapor pressure, meaning they readily evaporate and contribute to the overall vapor pressure of the solution.
* Boiling Point: A solution boils when its vapor pressure equals the atmospheric pressure. The higher the vapor pressure of the solution, the lower the temperature at which it will boil.
* Raoult's Law: This law states that the vapor pressure of a solution is proportional to the mole fraction of the solvent (water in this case). When a volatile solute is added, it decreases the mole fraction of water, leading to a lower vapor pressure and therefore a lower boiling point.
Example:
Adding ethanol (a volatile substance) to water will lower the boiling point of the resulting solution. This is because ethanol has a higher vapor pressure than water. The presence of ethanol increases the overall vapor pressure of the solution, causing it to boil at a lower temperature.
Important Note: The extent to which the boiling point is lowered depends on the concentration and volatility of the soluble volatile substance. More concentrated solutions and more volatile substances will have a greater effect on the boiling point.
