Question

a 250ml sample of 0.2m cr+3 is electrolysed with a current of 96.5a

Answer 1

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Answer 2

Answer:

75 sec

Explanation:

0.2 M is becoming 0.1M means decrease in Cr3+ concentration is 0.1M. Number of moles = M*V= 0.1*250*10-3 =25*10-3 moles.

1mole of Cr+3 requires 3F electrons to get electrolysed. So 25*10-3 moles requires 75*10-3F.

As q=i*t

75*10-3*96500 = 96.5 * t   (1F=96500 Columbs).

So t = 75 seconds.