discuss deviation from raoults law with suitable example. explain Both deviations through graph
Dear Student,
Deviation from Raoult's law occurs in two types :
1. Positive deviation : Let us consider a binary solution having component A and B. If the forces of attraction between molecules of A and B in the solution are weaker than that of between A-A and B-B , then the tendency of escaping of molecules A-B from the solution will be more than that in the pure liquid. The total vapour pressure of the solution will be greater than the corresponding vapour pressure of ideal solution of the sample component A and B. This type of solution shows positive deviation from Raoult's law. This reaction is endothermic in nature i.e. some energy is used during the reaction. ΔH = +ve in this case.
2. Negative deviation : Let us consider a binary solution having component A and B. If the forces of attraction between molecules of A and B in the solution are stronger than that of between A-A and B-B , then the tendency of escaping of molecules A-B from the solution becomes less than that in the pure liquid. The total vapour pressure of the solution will be lower than the corresponding vapour pressure of ideal solution of the sample component A and B. This type of solution shows negative deviation from Raoult's law. This reaction is exothermic in nature i.e. some energy is released during the reaction. ΔH = -ve in this case.
Deviation from Raoult's law occurs in two types :
1. Positive deviation : Let us consider a binary solution having component A and B. If the forces of attraction between molecules of A and B in the solution are weaker than that of between A-A and B-B , then the tendency of escaping of molecules A-B from the solution will be more than that in the pure liquid. The total vapour pressure of the solution will be greater than the corresponding vapour pressure of ideal solution of the sample component A and B. This type of solution shows positive deviation from Raoult's law. This reaction is endothermic in nature i.e. some energy is used during the reaction. ΔH = +ve in this case.
2. Negative deviation : Let us consider a binary solution having component A and B. If the forces of attraction between molecules of A and B in the solution are stronger than that of between A-A and B-B , then the tendency of escaping of molecules A-B from the solution becomes less than that in the pure liquid. The total vapour pressure of the solution will be lower than the corresponding vapour pressure of ideal solution of the sample component A and B. This type of solution shows negative deviation from Raoult's law. This reaction is exothermic in nature i.e. some energy is released during the reaction. ΔH = -ve in this case.