Which of the following solutions shows negative deviation from Raoult’s law?a)Acetone and chloroformb)Acetone and carbon disulphidec)Ethyl alcohol and cyclohexaned)Benzene and tolueneCorrect answer is option 'A'. Can you explain this answer?

Question

Which of the following solutions shows negative deviation from Raoult&#8217;s law?a)Acetone and chloroformb)Acetone and carbon disulphidec)Ethyl alcohol and cyclohexaned)Benzene and tolueneCorrect answer is option 'A'. Can you explain this answer?

Accepted Answer

Due to weakening of interactions, the solution shows positive deviation from Raoult's law. Mixture of chloroform and acetone forms a solution with negative deviation from Raoult's law. This is because chloroform molecule is able to form hydrogen bond with acetone molecule.

Answer

Solution:

Negative deviation from Raoult’s law occurs when the intermolecular forces between the components of the solution are stronger than the forces between the molecules of the pure components. This results in the vapor pressure of the solution being less than what is predicted by Raoult’s law.

Out of the given options, the solution of acetone and chloroform shows negative deviation from Raoult’s law.

Explanation:

Acetone and chloroform are two liquids that have different molecular structures and intermolecular forces. Acetone is a polar molecule with a carbonyl group that can form hydrogen bonds, whereas chloroform is a nonpolar molecule that has a dipole moment but cannot form hydrogen bonds. When these two liquids are mixed together, the polar and nonpolar molecules form weak intermolecular forces, resulting in a negative deviation from Raoult’s law.

The deviation from Raoult’s law can be explained by the fact that the intermolecular forces between acetone and chloroform molecules are weaker than the intermolecular forces between the molecules of the pure components. Thus, the vapor pressure of the solution will be lower than expected based on Raoult’s law.

Therefore, the correct option is A) Acetone and chloroform.

Answer

A solution of CHCL3  AND CH3COCH3 shows (-ve) deviation from Raoult's law》》molecules of pure chloroform and those of pure acetone cannot form H- bonds among themselves. however in a solution of chloroform and acetic anhydride, the hydrogen of CHCL3 is attacked by the O2  of acetic anhydride and thereby leads to the formation of H-bonds between the molecules of CHCL3 and (CH3)2CO molecules, which lower their tendency to escape from the solute. As a result  ,the partial vapour  pressure of CHCL3 and acetic anhydride and total vapor pressure of the solution becomes less than expected from Raoult's law.the strong forces of attraction between the molecules CHCL3 AND acetic anhydride leads to the lowering of potential energy of the system, which is accompanied with the evolution of heat..Hence,del H solution is negatives for the solution.

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