Question

Explain why a mixture of phenol and aniline shows a negative deviation from the rowlatt slow

Answer 1

The reason for negative deviation of phenol (A) and aniline(B) is explained as below.

Delta H mixing and Delta V mixing is less than zero. A-B attractive force should be greater than A-A and B-B attractive forces. 'A' and 'B' have different shape, size and character. Escaping tendency of both components 'A' and 'B' is lowered showing lower vapour pressure than expected ideally.

Answer 2

That is ethanol and carbon disulphide shows positive deviation because ethanol-CS2 shows weaker attractive forces. A-B attractive force should be greater than A-A and B-B attractive forces. ... ​For phenol - aniline it shows negative deviation because the attraction between phenol and aniline is more.