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 .

Question

An acidic solution of dichromate is electrolyzed for 8 minutes using 2 A current. As per the following equation

${Cr}_{2} O_{7}^{2} + 14 H^{+} + 6 e^{-} \to 2 {Cr}^{3 +} + 7 H_{2} O$
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 $= 52$ )

TestHub · Accepted Answer

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 %

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