Solution | Ideal and Non-Ideal Solutions
Differences between Ideal and Non-Ideal Solutions
| S.No | Ideal Solution | Non-Ideal Solution |
| 1 | The solutions which obey Raoult's law over the entire range of concentration are known as ideal solutions. | When a solution does not obey Raoult's law over the entire range of concentration, then it is called non-ideal solution. |
| 2 | For binary solution with components A and B, A-A type and B-B type interactions are equal to A-B type interactions. | For binary solution with components A and B, A-A type and B-B type interactions are not equal to A-B type interactions. |
| 3 | The enthalpy of mixing of the pure components to form the solution is zero (ΔHmix = 0). It means that no heat is absorbed or evolved when the components are mixed. | The enthalpy of mixing of the pure components to form the solution is not zero (ΔHmix ≠ 0), ie, it is either positive or negative. |
| 4 | The volume of mixing is also zero (ΔVmix = 0). It means the volume of solution would be equal to the sum of volumes of the two components. | The volume of mixing is not zero (ΔVmix ≠ 0), ie, it is either positive or negative. |
| 5 | Examples: Benzene+Toluene, CCl4+CS2 | Examples: Benzene+Water, Acetone+Ethanol |
Types of non-ideal solution
Non-ideal solutions can be further classified into two types: non-ideal solution with positive deviation and non-ideal solution with negative deviation.
| S.No | Non-Ideal Solution with positive deviation | Non-Ideal Solution with negative deviation |
| 1 | For binary solution, p > poAΧA + poBΧB | For binary solution, p < poAΧA + poBΧB |
| 2 | For binary solution with components A and B, A-A type and B-B type interactions are stronger than A-B type interactions. | For binary solution with components A and B, A-A type and B-B type interactions are weaker than A-B type interactions. |
| 3 | ΔHmix > 0. It means that heat is absorbed when the components are mixed. | ΔHmix < 0. It means that heat is evolved when the components are mixed. |
| 4 | ΔVmix > 0. It means the volume of solution would be greater than the sum of volumes of the two components. | ΔVmix < 0. It means the volume of solution would be less than the sum of volumes of the two components. |
| 5 | Example: Cyclohexane+Ethanol | Example: Methanol+Water |