Question

250 mL sample of a 0.20 M Cr³⁺ is electrolysed with a current of 96.5A. If the remaining [Cr³⁺] is 0.1M then the duration of process is: (Assume volume remain constant during process)

Answer 1

Initial moles of Cr³⁺ = 0.25 × 0.2 = 0.05 mol

Final moles of Cr³⁺ = 0.25 × 0.1 = 0.025 mol

Therefore moles of Cr³⁺ reduced is :

0.05 – 0.025 = 0.025 mol

or eq. of Cr³⁺ reduced 0.025 × 3 = \(\frac{{t \times 96.5}}{{96500}}\)

t = 75 sec