Colligative Properties of Solutions

Overview

Colligative properties of solutions are dependent on the number of solute and solvent molecules or ions, regardless of the solute's nature. These properties include the lowering of vapor pressure, elevation of boiling point, depression of freezing point, and osmotic pressure. They have practical applications in determining molecular mass and contributing to solution theory development.

Questions and Answers

  1. What are colligative properties of solutions?

    Colligative properties are properties of a solution that depend on the number of solute and solvent particles, such as lowering of vapor pressure, elevation of boiling point, depression of freezing point, and osmotic pressure.

  2. Why are colligative properties called so?

    Colligative properties are called so because they depend on the number of solute particles in a solution, not on the nature of the solute itself.

  3. How do you explain the lowering of vapor pressure as a colligative property?

    The lowering of vapor pressure is a colligative property because it depends on the number of solute particles present in the solution, leading to a decrease in the escaping tendency of the solvent molecules.

  4. What is the physical significance of Kb and Kf values of solvents?

    The Kb and Kf values of solvents are the molal boiling point constant and molal freezing point constant, respectively. They help in quantifying the extent of elevation in boiling point and depression in freezing point caused by the presence of solute particles in the solution.

  5. How do we measure the molar mass of a non-volatile, non-electrolyte solute in a volatile solvent?

    The molar mass of a non-volatile, non-electrolyte solute in a volatile solvent can be measured by utilizing colligative properties, such as depression in freezing point or elevation in boiling point, in conjunction with known constants like the molal freezing point constant or molal boiling point constant.

Multiple-Choice Questions

  1. Which of the following is a colligative property of solutions?

    a) Color
    b) Density
    c) Boiling Point Elevation
    d) Viscosity
    Answer: c) Boiling Point Elevation

  2. What does the lowering of vapor pressure depend on in a solution?

    a) Solute only
    b) Solvent only
    c) Both solute and solvent
    d) Temperature
    Answer: c) Both solute and solvent

  3. Which statement is true regarding colligative properties?

    a) They depend on the chemical nature of the solute
    b) They are not affected by the amount of solute
    c) They include osmotic pressure
    d) They are not applicable to dilute solutions
    Answer: c) They include osmotic pressure

  4. What happens to the freezing point of a solution when a non-volatile solute is added?

    a) It increases
    b) It decreases
    c) It remains the same
    d) It fluctuates
    Answer: b) It decreases

  5. Which property is not a colligative property of solutions?

    a) Osmotic Pressure
    b) Freezing Point Depression
    c) Color of the Solution
    d) Boiling Point Elevation
    Answer: c) Color of the Solution