Question

How many coulombs of electricity is required to reduce $1$ mole of $C{r}_2{O}_7^{2-}$ 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

The correct option is B $6\times 96500$ C

In acidic medium dichromate ions undergoes reduction and the reaction is,

$C{r}_2{O}_7+14H^{+}+6e^{-}\to 2C{r}^{3+}+7H_{2}O$

So, 1 mole of $C{r}_2{O}_7^{2-}$ ion requires 6 moles of electrons i.e. $6\times 96500$C of electricity