🧪

Solutions

Concentration, colligative properties, osmosis

Key Concepts
  • Colligative properties depend on number of solute particles, not their nature
  • Raoult's law: vapour pressure of solution is lowered by solute
  • Elevation of boiling point and depression of freezing point are colligative
  • Osmotic pressure: π = MRT (van't Hoff equation for dilute solutions)
  • Van't Hoff factor i > 1 for electrolytes; i < 1 for associated solutes
Important Formulae
Raoult's law P_solution = χ_solvent · P°_solvent
Boiling point elevation ΔTb = Kb · m · i
Freezing point depression ΔTf = Kf · m · i
Osmotic pressure π = MRT
Relative lowering of vapour pressure ΔP/P° = χ_solute
Quick Tips
  • For water: Kf = 1.86 K·kg/mol; Kb = 0.52 K·kg/mol.
  • Abnormal molar mass: electrolytes dissociate (i > 1), acetic acid in benzene dimerises (i < 1).
  • Isotonic solutions have equal osmotic pressure — important in IV drips.
Sample Practice Questions

  1. Elevation in boiling point: ΔTb = Kb × m. Kb is:

    • Molarity constant
    • Molal elevation constant (boiling point elevation constant)
    • Gas constant
    • Henry's constant
    Show answer

    Answer: Molal elevation constant (boiling point elevation constant)

  2. Mass % of solution = (mass of solute / total mass of solution) × :

    • 10
    • 100
    • 1000
    • 1
    Show answer

    Answer: 100

  3. Raoult's law for ideal solutions: p₁ = x₁ × p₁°. This means partial pressure is proportional to:

    • Molality
    • Mole fraction of component
    • Molarity
    • Mass fraction
    Show answer

    Answer: Mole fraction of component

  4. What type of solution shows positive deviation from Raoult's law?

    • Chloroform-acetone
    • Ethanol-water (partially)
    • Nitric acid-water
    • Phenol-aniline
    Show answer

    Answer: Ethanol-water (partially)

Practise 20 questions →
Practice Questions

Practice 20 randomly selected NEET questions on Solutions. Answers are revealed after each question.

Start Practice →
Chemistry Topics