Ideal and Non-ideal Solution: The binary solutions may be classified into two types:
- Ideal solutions
- Non-ideal solutions
Ideal solutions: Ideal solutions obey Raoult’s law exactly at all concentrations and temperatures. Such solutions are formed by mixing the two components which are identical in molecular size, in structure and have almost identical intermolecular forces.
PA = PA° XB
Non-Ideal Solution: The solutions which do not obey Raoult’s law and are accompanied by change in enthalpy and volume during their formation are called non-ideal solution. Therefore, for non-ideal solution,
PA ≠ P°A XB
NB:
1) A non-ideal solution shows positive deviation when solute-solvent interaction in solution is less than both solute-solute and solvent-solvent interactions.
2) A non-ideal solution shows negative deviation when solute-solvent interaction in solution is more than both solute-solute and solvent-solvent interactions.