Question

During the electrolysis of molten sodium chloride, the time required to produce 0.10 mol of chlorine gas using a current of 3 amperes is approximately:

• A. 220 minutes
• B. 330 minutes
• C. 55 minutes
• D. 110 minutes

Answer 1

Answer: (D)

Given

Equivalent weight of chlorine = $\frac{Molecularweightofchlorine}{n-factor}=\frac{35.5}{1}=35.5g$

Electric current passed = 3 amperes

Number of moles = 0.10 mole

Weight of 2 chlorine ions = $Numberofmoles\times Molecularmass$

Step 1:

At Cathode: $2H_{2}O+2e^{-}⟶H_2+2O{H}^{-}$

At Anode: $2{Cl}^{-}⟶{Cl}_2+2e^{-}$

Step 2:

Applying Faraday's Law

$W=\frac{E\times It}{96500}$

W is the weight of substance deposited

E is the equivalent weight of the substance

I is the electric current passed

t is the time in sec

$0.1\times 71=\frac{35.5\times t\left(sec\right)\times 3}{96500}$

$t=6433sec=107.2min\approx 110min$
Hence, option (D) is correct.