Solutions
1.0 Solution
2.0 Methods of expressing concentration of a Solution
3.0 Solubility
4.0 Henry's law
5.0 Raoult's law
6.0 Azotropes
7.0 Colligative Properties
7.1 Relative lowering of vapour pressure
7.2 Elevation in Boiling point
7.3 Depression of Freezing point
7.4 Osmosis and Osmotic pressure
8.0 Abnormal Colligative Properties
5.3 Non Ideal Solution
7.2 Elevation in Boiling point
7.3 Depression of Freezing point
7.4 Osmosis and Osmotic pressure
It is solution which donot obey Raoult's law at entire range of concentration. It means vapour pressure predicted by Raoult's law is not equal to vapour pressure founded practically.
- If vapour pressure is high then predicted by Raoult's law then it is said that solution shows positive deviation. Vapour pressure found practically is more it implies that the new bonds formed in solution are weaker than the bonds of components mixed. As bonds are weak, solution molecules can escape easily.
For positive deviation $A-B < A-A or B-B$ and $\Delta {V_{mix}} > 0$,$\Delta {V_{mix}} > 0$ , $\Delta {H_{mix}} > 0$.
Examples of Positive deviation:
1) Ethenol+Acetone (Before mixing there were strong $H$ bonds in Ethenol, which are raptured after mixing leading to positive deviation).
2) Carbondisulphide+acetone.
- If vapour pressure is low then predicted by Raoult's law then it is said that solution shows negative solution. Vapour pressure found practically is less it implies that the new bonds formed in solution are stronger than the bonds in component mixed. As bonds are strong, solution molecules can not escape easily.
For negative deviation $A-B > A-A or B-B$ and $\Delta {V_{mix}} < 0$ , $\Delta {H_{mix}} < 0$.
Examples of Negative deviation:
1) Phenol+ Aniline (After mixing strong $H$ bonds are formed between $H$ of $OH$ on phenol and lone pair on $N{H_2}$ of Aniline.
2) Chloroform+ Acetone
Following graphs represents the positive and negative deviation from Raoult's law,
