Engineering
Chemistry
Electrolytic Conductance
Question

Resistance of 0.2 M solution of an electrolyte is 50 Ω. The specific conductance of the solution is 1.4 S m–1. The resistance of 0.5 M solution of the same electrolyte is 280 Ω. The molar conductivity of 0.5 M solution of the electrolyte in S m2 mol–1 is

5 × 102

5 × 103

5 × 10–4

5 × 10–3

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Solution

K = 4.4*

For 0.2 M-solution1.4=150×4*:  ...(1)

For 0.5 M-solution: K =  1280× 4*   ...(2)

From (1) / (2), k = Sm–1

Now,

λm=14Sm10.5×103moℓm3

= 5 × 10–4 S m2 mol–1

               OR

Concentration = 0.2

Rsolution = 50 ohm

K = 1.4 S m–1

Concentration = 0.5

Rsolution = 280 ohm

K=1Resistancecell constant

1.4100=150 × cell constant

0.7 = cell constant

 λm=(1280×0.7)×10000.5

= 700×2280 = S cm2/mΩ

= 5 × 10–4 S m2/mΩ