A mixture of chlorobenzene and bromobenzene forms nearly ideal solution but a mixture of chloroform and acetone does not. Why?
An ideal solution is formed when two component which are used to form solution have almost similar interaction. Ideal solution follow Raoult's law at all concntrations. So no new interaction is developed in solution after mixing hence no change of enthalpy and volume is observed in solution. In that case
Vmixing and H mixing​ becomes zero.
When we mix chlorobenzene and bromobenzene , no new interaction is develop in solution as chlorobenzene and bromobenzene have almost similar constituents and have similar polarities. So, there is no change in enthalpy and volume of solution after mixing. It gives Ideal solution on mixing.
Vmixing and H mixing​ becomes zero.
When we mix chlorobenzene and bromobenzene , no new interaction is develop in solution as chlorobenzene and bromobenzene have almost similar constituents and have similar polarities. So, there is no change in enthalpy and volume of solution after mixing. It gives Ideal solution on mixing.
But, in case of mixing of chloroform and acetone, there is new force of attraction develop between the acetone and chloroform molecule. There is formation of a hydrogen bond between the hydrogen of CHCl3 and oxygen atom of CH3-CO-CH3 .
Hence the intermolecular interaction between chloroform and acetone is stronger than the intermolecular interactions of chloroform-chloroform and acetone -acetone molecules. This give rise to change in enthalpy and volume of solution after mixing. So, mixing of chloroform and acetone does not give ideal solution.