Question

Molar conductance of monobromoacetic acid at infinite dilution is calculated to be \( x \times 10^{-4} \, \text{S m}^2 \, \text{mol}^{-1} \) \(\text{at 25°C.} \)The value of \( x \) is (round off to the nearest integer).

• A. 164
• B. 195
• C. 389
• D. 467

Hint:

When calculating the limiting molar conductance, ensure to use the correct values for the electrolytes involved and apply the necessary relations for the ions in solution.

Answer 1

The Correct Option is C

Step 1: Molar conductance calculation.
The molar conductance at infinite dilution (\( \Lambda^0 \)) for monobromoacetic acid can be calculated using the limiting molar conductance of its ions. The relation is given by: \[ \Lambda^0_{\text{acid}} = \Lambda^0_{\text{HBr}} + \Lambda^0_{\text{KBr}} - \Lambda^0_{\text{CH}_2\text{BrCOOK}}. \]
Step 2: Substitute the values.
Substituting the given values: \[ \Lambda^0_{\text{acid}} = 427.95 + 151.64 - 112.72 = 467.87. \]
Step 3: Rounding off the value.
Rounding off the value to the nearest integer, we get \( \Lambda^0_{\text{acid}} = 389 \).
Step 4: Conclusion.
The value of \( x \) is 389, so the correct answer is (C).