Benzene and toluene form an ideal solution at room temperature. Which Of the following is not true for this process?

Options

A. `DeltaV_(mix)=0`
B. `DeltaH_(mix)=0`
C. `DeltaS_(mix)`for system=0`
D. `DeltaG_(mix)lt 0`

Answer

To solve the question regarding the properties of an ideal solution formed by benzene and toluene, we need to analyze the statements provided and determine which one is not true.

### Step-by-Step Solution:

1. **Understanding Ideal Solutions**:
- An ideal solution is one that obeys Raoult's law, meaning that the vapor pressure of each component in the solution is proportional to its mole fraction in the mixture.
- The intermolecular forces between the molecules of the components (A and B) are similar, i.e., the attraction between A-A, B-B, and A-B are approximately equal.

2. **Evaluating the Statements**:
- **Statement 1**: \( \Delta V_{\text{mixture}} = 0 \)
- This statement is true for ideal solutions. When two liquids mix ideally, there is no change in volume upon mixing.

- **Statement 2**: \( \Delta H_{\text{mixture}} = 0 \)
- This statement is also true. The enthalpy change for an ideal solution is zero, indicating that there is no heat absorbed or released during the mixing process.

- **Statement 3**: \( \Delta S_{\text{mixture}} = 0 \)
- This statement is not true. For an ideal solution, the entropy change (\( \Delta S_{\text{mixture}} \)) is positive because mixing increases the disorder of the system. Thus, \( \Delta S_{\text{mixture}} > 0 \).

- **Statement 4**: \( \Delta G_{\text{mixture}} < 0 \)
- This statement is true. The Gibbs free energy change (\( \Delta G_{\text{mixture}} \)) for a spontaneous process (like the formation of an ideal solution) is negative.

3. **Conclusion**:
- The statement that is not true for the process of forming an ideal solution of benzene and toluene is **Statement 3**: \( \Delta S_{\text{mixture}} = 0 \).

### Final Answer:
The statement that is not true is: **\( \Delta S_{\text{mixture}} = 0 \)**.