Question

How many coulombs of electricity is required to reduce 1 mole of $Cr_{2}O_{7}^{2 -}$ in acidic medium?

• A. $4 \times 96500C$
• B. $6 \times 96500C$
• C. $2 \times 96500C$
• D. $1 \times 96500C$

Answer 1

Answer: (B)

$6 \times 96500C$

Answer 2

In acidic medium dichromate ions are reduced according to the equation,

$CrO_{7}^{2 -} + 14H^{+} + 6e^{-} \rightarrow 2Cr^{3 +} + 7H_{2}O$

1 mole of $Cr_{2}O_{7}^{2 -}$ ion requires 6 moles of electrons or $6 \times 96500$ C of electricity.