When ethanol mixes in cyclohexane, cyclohexane reduces the intermolecular forces between ethanol molecule. In this, liquid pair shows

Options

A. Positive deviation by Raoult's law
B. Negative deviation by Raoult's law
C. No deviation by Raoult's law
D. Decrease in volume

Answer

To solve the question regarding the mixing of ethanol and cyclohexane and the resulting intermolecular forces, we can break down the explanation step by step.

### Step-by-Step Solution:

1. **Identify the Nature of the Liquids**:
- Ethanol (C2H5OH) is a polar molecule due to the presence of the hydroxyl (-OH) group.
- Cyclohexane (C6H12) is a non-polar molecule as it consists of a hydrocarbon structure without any polar functional groups.

**Hint**: Remember that polarity is determined by the presence of electronegative atoms and the molecular structure.

2. **Understand Intermolecular Forces**:
- In pure ethanol, the intermolecular forces are primarily hydrogen bonds due to the -OH group.
- In pure cyclohexane, the intermolecular forces are London dispersion forces, which are weaker than hydrogen bonds.

**Hint**: Different types of intermolecular forces have varying strengths; hydrogen bonds are stronger than dispersion forces.

3. **Mixing of Ethanol and Cyclohexane**:
- When ethanol and cyclohexane are mixed, the polar ethanol molecules interact with the non-polar cyclohexane molecules.
- The presence of cyclohexane disrupts the hydrogen bonding between ethanol molecules, leading to a reduction in the overall intermolecular forces.

**Hint**: Mixing polar and non-polar substances often leads to a disruption of the stronger polar interactions.

4. **Analyze the Resulting Intermolecular Forces**:
- The interaction between ethanol and cyclohexane (AB interactions) is weaker than the interactions within pure ethanol (AA interactions) and pure cyclohexane (BB interactions).
- This leads to a situation where the total intermolecular forces in the mixture are less than those in the pure components.

**Hint**: Compare the strength of interactions: AA and BB are stronger than AB.

5. **Conclusion Based on Raoult's Law**:
- According to Raoult's Law, when the intermolecular forces between the components in a mixture are weaker than those in the pure substances, it results in a positive deviation from Raoult's Law.
- Therefore, the liquid pair of ethanol and cyclohexane shows positive deviation.

**Hint**: Positive deviation indicates that the vapor pressure of the mixture is higher than expected based on the pure components.

### Final Answer:
The liquid pair of ethanol and cyclohexane shows positive deviation from Raoult's Law due to the reduction of intermolecular forces when mixed.