Question

Describe the oxidising action of potassium dichromate and write the ionic equations for its reaction with

(i) Iodide

(ii) Iron

(iii) $H_{2}S$

Answer 1

Potassium dichromate is a strong oxidising agent. In acidic solution, its oxidising action may be represented as:
$C{r}_2{O}_7^{2-}+14H^{+}+6e^{-}\to 2C{r}^{3+}+7H_{2}O(E^{\circ }=1.33V)$
Ionic Equations
Reaction of $K_{2}C{r}_2{O}_7$ with $I^{-}$
$C{r}_2{O}_7^{2-}+14H^{+}+6I^{-}\to 2C{r}^{3+}+3I_2+7H_{2}O$

Potassium dichromate is a strong oxidising agent. In acidic solution, its oxidising action may be represented as:

$C{r}_2{O}_7^{2-}+14H^{+}+6e^{-}\to 2C{r}^{3+}+7H_{2}O(E^{\circ }=1.33V)$

Ionic Equations
Reaction of $K_{2}C{r}_2{O}_7$ with $F{e}^{2+}\left(aq\right)$
$C{r}_2{O}_7^{2-}+14H^{+}+6F{e}^{2+}\to 2C{r}^{3+}+6F{e}^{3+}+7H_{2}O$

Potassium dichromate is a strong oxidising agent. In acidic solution, its oxidising action may be represented as:
$C{r}_2{O}_7^{2-}+14H^{+}+6e^{-}\to 2C{r}^{3+}+7H_{2}O(E^{\circ }=1.33V)$

Ionic Equations
Reaction of $K_{2}C{r}_2{O}_7$ with $H_{2}S$
$C{r}_2{O}_7^{2-}+8H^{+}+3H_{2}S\to 2C{r}^{3+}+3S+7H_{2}O$