A binary liquid solution is prepared by mixing n-heptane and ethanol. Which one of the following statements is correct regarding the behaviour of the solution?

Options

A. The solution formed is an ideal solution
B. The solution is non-ideal, showing +ve deviation from Raoult's law
C. The solution is non-ideal, showing -ve deviation from Raoult's law
D. n-heptane shows +ve deviation while ethanol shows - ve deviation from Raoult's law

Answer

To analyze the behavior of the binary liquid solution formed by mixing n-heptane and ethanol, we can follow these steps:

### Step 1: Identify the Components
We have two components in the solution:
- **n-Heptane (C7H16)**: This is a non-polar hydrocarbon.
- **Ethanol (C2H5OH)**: This is a polar molecule due to the presence of the hydroxyl (-OH) group.

### Step 2: Understand the Intermolecular Forces
- **n-Heptane**: Exhibits Van der Waals forces (dispersion forces) since it is non-polar.
- **Ethanol**: Exhibits hydrogen bonding due to the -OH group, which is a strong intermolecular force.

### Step 3: Mixing the Components
When n-heptane and ethanol are mixed:
- The hydrogen bonds in ethanol will be disrupted due to the presence of n-heptane.
- The interactions between n-heptane (A-A) and ethanol (B-B) will be replaced by A-B interactions.

### Step 4: Analyze the Change in Intermolecular Forces
- The intermolecular forces in the mixed solution (A-B interactions) are weaker than the original A-A (n-heptane) and B-B (ethanol) interactions.
- This results in a decrease in the overall intermolecular attraction in the solution.

### Step 5: Effect on Vapor Pressure
- Since the intermolecular forces are weaker in the solution, the vapor pressure of the solution will increase compared to the pure components.
- According to Raoult's Law, if the vapor pressure of the solution is greater than expected, it indicates a positive deviation from ideal behavior.

### Step 6: Conclusion
Based on the analysis, the correct statement regarding the behavior of the solution is:
- **The solution is non-ideal showing positive deviation from Raoult's Law.**

### Final Answer
The correct option is: **The solution is non-ideal showing positive deviation from Raoult's Law.**

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