Question

What volume of $0.05M{K}_{2}C{r}_2{O}_7$ in acidic medium is needed for complete oxidation of $200mL$ of $0.06M$ $Fe{C}_2{O}_4$ solution?

• A. $1.2mL$
• B. $1.2L$
• C. $120mL$
• D. $800mL$

Answer 1

Answer: (B)

$\underset{0.05M}{C{r}_2{O}_7^{2-}}+\underset{0.6M/200mL}{Fe{C}_2{O}_4}\stackrel{H^{\oplus }}{\to }$
$C{r}_2{O}_7^{2-}+14H^{\oplus +}+6e^{-}\to 2C{r}^{3+}+7H_{2}O$
$F{e}^{2+}\to F{e}^{+3}+e^{-}$
$C_2{O}_4^{2-}\to 2C{O}_2+2e^{-}$
$Fe{C}_2{O}_4\to F{e}^{3+}+2C{O}_2+3e^{-}$
$mE{q}_2$ of $K_{2}C{r}_2{O}_7\equiv Fe{C}_2{O}_4$
$(0.05\times 6)\times V=(0.6\times 3)\times 200$
$\Rightarrow V=1200mL=1.2L$