Colligative Properties of Solutions Chemistry Notes
→ Those properties of solutions which depend on number of moles of solute particles present in certain volume of solution are called colligative properties of solutions. Colligative properties do not depend on chemical properties or nature of solute, but these depend on number of molecules.
→ Example If one mole of sugar or urea is dissolved in 100 mL water then the solution so obtained will possess always same elevation of boiling point or lowering of vapour pressure. Colligative properties in solution a number of particles or molecules In these properties, ions also behave as particles.
Colligative Properties :
Following are some important colligative properties.
- Lowering of vapour pressure of solvent
- Elevation in boiling point of solvent
- Depression in freezing point of solvent
- Osmotic pressure of solvent
Some Important facts about Colligative Properties of Solution :
→ The aqueous solutions of non-electrolytes like urea, glucose, sugar etc of same molar concentration have same colligative properties like osmotic pressure (π), elevation of boiling point (∆T) etc at same temperature. In these colligative properties, ions behave as molecules or particles.
→ The colligative properties of aqueous solutions of urea, NaCl, CaCl2, Na3PO4 of same molar concentration are not similar. Its reason is that electrolyter give ions on isssociation in water. The number of ions obtained from electroytes can be different. So it is not necessary that the colligative properties of solutions of electrolytes of same molar concentrations in same conditions are same.
→ The colligative properties of solutions of two different substances will be equal, if the total number of ions of solute and molecules present in certain volume of solution is same.
→ The colligative properties are inversily proportional to molecular mass of solute (while molecular mass is not a colligative property) Colligative property.