Question

Write correctly balanced half reaction and overall equation for the following skeletal equation :
A) ${NO}_3^{-}+Bi\left(s\right)\to {Bi}^{3+}+{NO}_2$ (in acid solution)
B) $Fe{\left(OH\right)}_3\left(s\right)+H_2{O}_2\to Fe{\left(OH\right)}_2\left(s\right)+H_{2}O+O_2$ (in basic medium)
C) ${Cr}_2{O}_7^{2-}+C_2{H}_{4}O\to C_2{H}_4{O}_2+{Cr}^{3+}$ (in acid solution)

Answer 1

(a)

Equal increasing and decreasing oxidation number

$3N{O}_3^{-}+Bi\to Bi+3+3N{O}_2$

Balance charge by $H^{+}$ (due to acidic medium) hydrogen by $H_{2}O$

$3N{O}_3^{-}+Bi+6H+\to B{i}^{+3}+3N{O}_2+3H_{2}O$

(b)

Equal increasing and decreasing oxidation number

$2Fe(OH{)}_3+H_2{O}_2\to 2Fe(OH{)}_2+H_{2}O+O_2$

Balance hydrogen by $H_{2}O$ and then oxygen by $O_2$

$2Fe(OH{)}_3+H_2{O}_2\to 2Fe(OH{)}_2+2H_{2}O+2O_2$

(c)

Equal increase and decrease

$C{r}_2{O}_7^2+3C_2{H}_{4}O\to 3C_2{H}_4{O}_2+2^{C_r+3}$

Balance hydrogen by $H^{+}$ and $H_{2}O$ and charge is also balanced

$C{r}_2{O}_7^2+3C_2{H}_{4}O+8iH+\to 3C_2{H}_4{O}_2+2C{r}^{++3}+4H_{2}O$