Question

In the following redox reaction,
$C{r}_2{O}_7^{2-}+F{e}^{2+}\to F{e}^{3+}+C{r}^{3+}1$ mole of $C{r}_2{O}_7^{2-}$ oxidises

• A. 1 mole of $F{e}^{2+}$
• B. 3 moles of $F{e}^{2+}$
• C. 4 moles of $F{e}^{2+}$
• D. 6 moles of $F{e}^{2+}$

Answer 1

Answer: (D)

$C{r}_2{O}_7^{2-}+F{e}^{2+}\to F{e}^{3+}+C{r}^{3+}$

$Cr$-atoms
Change in $O.N.]6$ units

Change in $O.N.]1$ unit
By cross-multiplication
$C{r}_2{O}_7^{2-}+6F{e}^{2+}\to 6F{e}^{3+}+2C{r}^{3+}$
$1molC{r}_2{O}_7^{2-}=6molFe{}^{2+}$