Question

Which of the following equations is NOT correct for van’t Hoff factor?

• A. \( i = \frac{n(\text{observed})}{n(\text{theoretical})} \)
• B. \( i = \frac{\text{theoretical molar mass}}{\text{observed molar mass}} \)
• C. \( i = \frac{\text{observed molar mass}}{\text{theoretical molar mass}} \)
• D. \( i = \frac{\pi (\text{observed})}{\pi (\text{theoretical})} \)

Hint:

Van’t Hoff factor (\(i\)) relates to the ratio of observed to theoretical values, typically considering the number of particles in solution.

Answer 1

The Correct Option is C

Step 1: Understanding the van’t Hoff factor.
The van’t Hoff factor (\(i\)) is the ratio of the observed colligative property to the theoretical colligative property. The correct equation for the van’t Hoff factor is the ratio of the observed molar mass to the theoretical molar mass for the solute.
Step 2: Analyzing the options.
(A) \( i = \frac{n(\text{observed}){n(\text{theoretical})} \):} Correct. This is a valid equation for van’t Hoff factor.
(B) \( i = \frac{\text{theoretical molar mass}}{\text{observed molar mass}} \): Correct. This is another valid equation for calculating \(i\) based on molar masses.
(C) \( i = \frac{\text{observed molar mass}}{\text{theoretical molar mass}} \): Incorrect — This equation is incorrect for calculating the van’t Hoff factor. It should be the inverse of this.
(D) \( i = \frac{\pi (\text{observed}){\pi (\text{theoretical})} \):} Correct. This is another valid equation for van’t Hoff factor.
Step 3: Conclusion.
The correct answer is (C) \( i = \frac{\text{observed molar mass}}{\text{theoretical molar mass}} \), as it is the incorrect equation for van’t Hoff factor.