The molar conductivity of 0.10 M solution of MgCl2 is 100 mho cm^2 mol^–1, at 25°C. A cell with electrodes that are 1.50 cm^2 in surface area and 0.50 cm apart is filled with 0.10 M – MgCl2 solution.

Question

The molar conductivity of 0.10 M solution of MgCl2 is 100 mho cm^2 mol^–1, at 25°C. A cell with electrodes that are 1.50 cm^2 in surface area and 0.50 cm apart is filled with 0.10 M – MgCl2 solution. How much current will flow when the potential difference between the electrodes is 5 volts?

Prashant Kotian · Accepted Answer

Correct answer: C. Specific conductance κ = (Molar conductivity × Molarity) / 1000 = (100 × 0.10) / 1000 = 0.01 S cm^–1. Cell constant G* = length / Area = 0.50 / 1.50 = 1/3 cm^–1. Resistance R = G* / κ = (1/3) / 0.01 = 100/3 Ω. Current I = V / R = 5 / (100/3) = 15 / 100 = 0.15 A. Therefore, correct answer is C.

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