A mixture of cyclohexane and ethanol shows

Options

A. ideal solution behaviour
B. negative deviation from Rault's law
C. positive deviation from Rault's low
D. cannot be predicted

Answer

To solve the question regarding the mixture of cyclohexane and ethanol, we can follow these steps:

### Step 1: Understand the Components
- Cyclohexane (C6H12) is a non-polar solvent.
- Ethanol (C2H5OH) is a polar solvent with hydrogen bonding.

**Hint:** Identify the properties of each component to understand their interactions.

### Step 2: Identify Intermolecular Forces
- Ethanol exhibits strong intermolecular forces due to hydrogen bonding.
- Cyclohexane, being non-polar, does not form hydrogen bonds and has weaker van der Waals forces.

**Hint:** Consider how the intermolecular forces affect the behavior of the mixture.

### Step 3: Apply Raoult's Law
- Raoult's Law states that the vapor pressure of a component in a solution is equal to the mole fraction of that component multiplied by the vapor pressure of the pure component.
- In this case, we need to consider that the addition of cyclohexane disrupts the hydrogen bonding in ethanol.

**Hint:** Recall how Raoult's Law applies to solutions with volatile components.

### Step 4: Analyze the Mixing Process
- When cyclohexane is added to ethanol, it interferes with the hydrogen bonding between ethanol molecules.
- This disruption requires energy, indicating that the enthalpy of mixing (ΔH) is positive.

**Hint:** Think about the energy changes involved when mixing different types of molecules.

### Step 5: Consider Volume Changes
- The breaking of hydrogen bonds and the introduction of cyclohexane increases the volume of the solution, meaning the change in volume (ΔV) is also positive.

**Hint:** Relate volume changes to the interactions between the molecules in the mixture.

### Step 6: Determine the Type of Deviation from Raoult's Law
- Since the mixture shows a positive deviation from Raoult's Law, this means the vapor pressure of the solution is higher than expected for an ideal solution.
- This is due to the weaker interactions in the mixture compared to the pure components.

**Hint:** Identify the characteristics of positive and negative deviations from Raoult's Law.

### Step 7: Conclusion
- The mixture of cyclohexane and ethanol exhibits a positive deviation from Raoult's Law, indicating that it behaves as a non-ideal solution.
- Therefore, the correct answer to the question is that the mixture shows positive deviation from Raoult's Law.

**Final Answer:** The mixture of cyclohexane and ethanol shows positive deviation from Raoult's Law.