Question

How long should aqueous \(\text{NaCl}\) be electrolysed by passing 100 ampere current, so that 0.5 mol chlorine is released at anode?

• A. 96500 seconds
• B. 9650 seconds
• C. 965 seconds
• D. 96.5 seconds

Hint:

Find the charge needed to liberate the given moles of chlorine and divide by the current.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept
At the anode, \(2\text{Cl}^{-}\rightarrow\text{Cl}_2+2e^{-}\). Each mole of \(\text{Cl}_2\) needs 2 mol of electrons.

Step 2: Charge required
For 0.5 mol \(\text{Cl}_2\), electrons needed \(=1\text{ mol}\), so \(Q=1\times96500=96500\text{ C}\).

Step 3: Time
\(t=\frac{Q}{I}=\frac{96500}{100}=965\text{ s}\).

Step 4: Compare the options
The time is 965 seconds, the third option.

Final Answer:
The electrolysis must run for 965 seconds. \[ \boxed{\text{(C) }965\text{ seconds}} \]