An acidic solution of dichromate is electrolyzed for 8 minutes using 2 A current. As per the following equation Cr 2 O 7 2 + 14 H + + 6 e - → 2 Cr 3 + + 7 H 2 O The amount of Cr 3 + . obtained was 0 . 104 g . The efficiency of the process ( in % ) is (Take : F = 960000 C , At. mass of chromium = 52 )

Step-by-step solution

Charge q = it = 2 × 8 × 60 = 960   C 960 96000 = 0 . 01 F Cr 2 O 7 2 - + 14 H + + 6 e -   →     2 Cr 3 +   +   7 H 2 O 0 . 01 F       1 3 × 0 . 01   mole Theoritical mass of Cr 3 + = 1 3 × 600 96000 × 52 = 0 . 173 g So, efficiency = W actual W Theoritial × 100 = 0 . 104 0 . 173 × 100 = 60 %