Question

A 0.02 M KCl solution has conductivity \(k=2.76\times 10^{-3}\ \text{S cm}^{-1}\). Find molar conductivity.

• A. \(130\ \text{S cm}^{2}\text{mol}^{-1}\)
• B. \(138\ \text{S cm}^{2}\text{mol}^{-1}\)
• C. \(148\ \text{S cm}^{2}\text{mol}^{-1}\)
• D. \(150\ \text{S cm}^{2}\text{mol}^{-1}\)

Hint:

Use molar conductivity = conductivity x 1000 / molarity with conductivity in S per cm.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
Molar conductivity is \(\Lambda_m=\dfrac{\kappa\times1000}{M}\), with \(\kappa\) in \(\text{S cm}^{-1}\) and \(M\) in mol/L.

Step 2: Substitute
\(\Lambda_m=\dfrac{2.76\times10^{-3}\times1000}{0.02}\).

Step 3: Calculation
\(\Lambda_m=\dfrac{2.76}{0.02}=138\ \text{S cm}^{2}\text{mol}^{-1}\).

Final Answer:
The molar conductivity is \(138\ \text{S cm}^{2}\text{mol}^{-1}\). \[ \boxed{\text{(B) }138\ \text{S cm}^{2}\text{mol}^{-1}} \]