Question

Give one example of miscible liquid pair which shows negative deviation from Raoult’s law. What is the reason for such deviation?

Answer 1

An example of a miscible liquid pair showing negative deviation from Raoult’s law is acetone and chloroform. The reason for this deviation is that the intermolecular forces between acetone and chloroform molecules are stronger than those between acetone molecules or chloroform molecules alone. This stronger attraction leads to a reduction in vapor pressure, resulting in negative deviation from Raoult’s law.

Answer 2

Raoult’s law states that the partial vapor pressure of each volatile component in a solution is directly proportional to its mole fraction in the solution. It is mathematically expressed as:

Raoult's Law Formula:
\( P_A = x_A \cdot P_A^0 \)

Where:

• P_A is the partial vapor pressure of component A,
• x_A is the mole fraction of component A in the solution,
• P_A⁰ is the vapor pressure of pure A.

Answer 3

Raoult’s law is a special case of Henry’s law. Henry’s law applies to the solubility of gases in liquids, where the partial pressure of the gas is directly proportional to its mole fraction in the solution. Raoult’s law can be considered a special case of Henry’s law when dealing with volatile components, where the solvent is also volatile, and both components behave simi- larly. Thus, Raoult’s law applies to solutions of volatile liquids, which is a subset of Henry’s law.

Answer 4

Two characteristics of an ideal solution are:

1. The enthalpy of mixing (\( \Delta H_{\text{mix}} \)) is zero.
2. The volume of mixing (\( \Delta V_{\text{mix}} \)) is also zero.