Give two examples of each of the liquids pairs for which ∆mixing H is negative ad positive respectively.
Answers
Answer:
- Two examples of the liquids pairs for which ∆mixing H is negative are :-
1. Chloroform + Benzene
2. Acetone + Aniline
- Two examples of the liquids pairs for which ∆mixing H is positive are :-
1. Acetone + Benzene
2. Methyl alcohol + water
Non ideal solutions with positive and negative deviation
Explanation:
Solutions
They are formed when solute and solvent are mixed together .
Types of solutions (depending upon whether they obey Raoult's law or not )
- Ideal solutions
- Non ideal solutions
Ideal solutions
They are those that obey Raoult's law at all range of temperature and pressure .
For them ΔHmixing =0
ΔVmixing =0
For them Pₐ = P°ₐ xₐ and similarly for P of b.
Example :
n-hexane and n-heptane
Non ideal solutions
The solution that do not obeys the Raoult's law at all condition of temperature and pressure .
They are of two types :
- Non ideal solution with positive deviation
- Non ideal solution with negative deviation
Non ideal solution with positive deviation
They have vapour pressure more than the Pure component A and B .
For them ΔHmixing = +ve
For them ΔVmixing = +ve
In them intermolecular forces of A-B are less than A-A and B-B.
Example :
Acetone and Carbon disulphide
Non ideal solutions showing negative deviation
They have vapour pressure less than the Pure component A and B as interactions between A-B is more than A-A and B-B.
For them ΔHmixing = -ve
For them ΔVmixing = -ve
In them intermolecular forces of A-B are more than A-A and B-B.
For example :
Chloroform and Benzene