Question

How many coulombs of electricity is required to reduce $1\, mole$ of $Cr_2O_7^{2-}$ in acidic medium?

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

Answer 1

Answer: (B)

In acidic medium, dichromate ions are reduced according to the equation,
$Cr_{2}O^{2-}_{7}+14H^{+}+6e^{-} \to2Cr^{3+}+7H_{2}O$
$1\, mole$ of $Cr_2O_7^{2-}$ ion requires $6 \,moles$ of electrons or $6 \times 96500 \,C$ of electricity.