Ideal and Non-Ideal solution
Table: Ideal and non-ideal solutions
| Ideal solutions | Non-ideal solutions | ||
| Positive deviation from Raoult's law | Negative deviation from Raoult's law | ||
| 1. Obey Raoult's law at every range of concentration. | 1. Do not obey Raoult's law. | 1. Do not obey Raoult's law. | |
2.  neither heat is evolved nor absorbed during dissolution. | 2.  Endothermic dissolution; heat is absorbed. | 2.  Exothermic dissolution; heat is evolved. | |
3.  total volume of solution is equal to sum of volumes of the components. | 3.  Volume is increased after dissolution. | 3.  Volume is decreased during dissolution. | |
4. | 4. | 4. | |
5.  interactions should be same, i.e., 'A' and 'B' are identical in shape, size and character. | 5.  attractive force should be weaker than  and  attractive forces. 'A' and 'B' have different shape, size and character. | 5. attractive force should be greater than and attractive forces. 'A' and 'B' have different shape, size and character. | |
| 6. Escaping tendency of 'A' and 'B' should be same in pure liquids and in the solution. | 6. 'A' and 'B' escape easily showing higher vapour pressure than the expected value. | 6. Escaping tendency of both components 'A' and 'B' is lowered showing lower vapour pressure than expected ideally. | |
Examples: Dilute solutions; benzene + toluene: n-hexane + n-heptane; chlorobenzene + bromobenzene; ethyl bromide + ethyl iodide; n-butyl chloride + n-butyl bromide | Examples: Acetone +ethanol acetone + water + methanol; water + ethanol; acetone + benzene; cyclohexane + ethanol | Examples: Acetone + aniline; acetone + chloroform;
chloroform + diethyl ether; water + HCl; acetic acid + pyridine; chloroform + benzene
| |
i.e.,
:
toluene;
;
;
;
Graphical representation of ideal and non-ideal solutions
