Question

Explain with suitable diagram and appropriate examples why some non-ideal solution show positive deviation from ideal behavior :

Answer 1

A non-ideal solution is a solution whose properties are generally not very predictable on account of the intermolecular forces between the molecules. None. Non-ideal solutions by definition cannot be dealt with through Raoult's Law. Raoult's Law is strictly for ideal solutions only.

A solution shows positive deviation from ideal behaviour when the interaction between them, unlike molecules, is weaker than the like molecules i.e interaction between A-B molecules is weaker than A-A and B-B molecules. In this case, the molecules find it more easy to escape an thus the vapour pressure of the solution is higher than expected. Example, when acetone is mixed with ethanol, energy, is required to break hydrogen bonds between ethanol molecules.