JEE Main 2020 — Electrochemistry Question with Solution
From: JEE Main 2020 (Online) 3rd September Evening Slot
Question
An acidic solution of dichromate is electrolyzed
for 8 minutes using 2A current. As per the
following equation
Cr2O72- + 14H+ + 6e– 2Cr3+ + 7H2O
The amount of Cr3+ obtained was 0.104 g. The efficiency of the process(in%) is (Take : F = 96000 C, At. mass of chromium = 52) ______.
Cr2O72- + 14H+ + 6e– 2Cr3+ + 7H2O
The amount of Cr3+ obtained was 0.104 g. The efficiency of the process(in%) is (Take : F = 96000 C, At. mass of chromium = 52) ______.
Enter your answer
Show full solutionCorrect answer: 60
Correct answer
60
Step-by-step explanation
Cr2O72-
+ 14H+ + 6e– 2Cr3+ + 7H2O
I = 2 A, t = 8 min
From 1st law of faraday,
wCr+3 = z i t
wCr+3 =
=
Mass of Cr3+ ions actually obtained = 0.104 gm
% efficiency =
= 100
= 60 %
I = 2 A, t = 8 min
From 1st law of faraday,
wCr+3 = z i t
wCr+3 =
=
Mass of Cr3+ ions actually obtained = 0.104 gm
% efficiency =
Actual obtained Amt
Theo. obtained Amt
100
= 100
= 60 %
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