Question 28 of 29beginner🔧 ApplyNumerical2 marks

The conductivity of 0.20 M solution of KCl at 298 K is 0.0248 S cm⁻¹. Calculate its molar conductivity.

Correct Answer

Given: Conductivity (κ\kappa) = 0.0248 S cm⁻¹ Concentration (cc) = 0.20 mol L⁻¹

Formula: Molar conductivity (Λm\Lambda_m) is calculated using the relation: Λm=κ×1000c\Lambda_m = \frac{\kappa \times 1000}{c}

Calculation: Substituting the given values in the formula: Λm=0.0248×10000.20\Lambda_m = \frac{0.0248 \times 1000}{0.20} Λm=24.80.20\Lambda_m = \frac{24.8}{0.20} Λm=124 S cm2 mol−1\Lambda_m = 124 \text{ S cm}^2 \text{ mol}^{-1}

Thus, the molar conductivity of the KCl solution is 124 S cm² mol⁻¹.

Exercise: EXERCISES | Q: 2.8 | (Chapter: Page 29)
For More Understanding

Explanation

The solution uses the standard formula for molar conductivity derived from the definition Λm=κ/c\Lambda_m = \kappa / c, where cc must be converted to mol m⁻³ or handled with the factor of 1000 when κ\kappa is in S cm⁻¹ and cc is in mol L⁻¹. This relationship is supported by the data in Table 2.3 of the provided context, which shows that multiplying conductivity (S cm⁻¹) by 1000 and dividing by molarity (mol L⁻¹) yields molar conductivity in S cm² mol⁻¹.

Solution Steps

  1. Step 1: Identify the given values: Conductivity (κ\kappa) = 0.0248 S cm⁻¹ and Concentration (cc) = 0.20 mol L⁻¹.

  2. Step 2: State the formula for molar conductivity when conductivity is in S cm⁻¹: Λm=κ×1000c\Lambda_m = \frac{\kappa \times 1000}{c}.

  3. Step 3: Substitute the values into the formula: Λm=0.0248×10000.20\Lambda_m = \frac{0.0248 \times 1000}{0.20}.

  4. Step 4: Calculate the result: Λm=124 S cm2 mol−1\Lambda_m = 124 \text{ S cm}^2 \text{ mol}^{-1}.

PreviousNext