Read the passage given below and answer the following questions: The p...
Colligative Properties
The properties of solutions that depend only on the number of solute particles but not on the nature of the solute are called colligative properties. Examples of colligative properties include:
- Relative lowering in vapour pressure
- Freezing point depression
- Boiling point elevation
- Osmotic pressure
Relative Lowering in Vapour Pressure
Relative lowering in vapour pressure is a colligative property that depends on the number of solute particles in a solution. It is defined as the ratio of the difference in vapour pressure of the pure solvent to the vapour pressure of the solution.
Experiment with Sugar Solution
In an experiment with sugar solution, we can measure the relative lowering in vapour pressure by comparing the vapour pressure of the pure solvent (water) with the vapour pressure of the sugar solution.
To perform this experiment, we need the following:
- A container with a known volume
- A thermometer to measure the temperature
- A barometer to measure the atmospheric pressure
- A sample of pure water
- A sample of sugar solution with a known concentration
First, we measure the temperature and atmospheric pressure. Next, we fill the container with pure water and measure the vapour pressure. Then, we empty the container and fill it with the sugar solution. We measure the vapour pressure of the sugar solution and calculate the relative lowering in vapour pressure.
The relative lowering in vapour pressure is directly proportional to the concentration of the solute. Therefore, we can use this property to determine the concentration of a solution.