Question

The yellow coloured solution of chromate salt changes to orange colour on acidification due to the formation of :

• A. $C{r}^{3+}$
• B. $C{r}_{2}O{{}_7}^{2-}$
• C. $CrO{{}_4}^{-}$
• D. $C{r}_2{O}_3$

Answer 1

The correct option is B $C{r}_{2}O{{}_7}^{2-}$

The yellow colored solution of chromate salt changes to orange color on acidification due to the formation of $C{r}_{2}O{{}_7}^{2-}$. In acidic medium, chromate ion changes to dichromate ion.
$\underset{yellow}{2CrO{{}_4}^{2-}}+2H^{+}\to \underset{orangered}{C{r}_{2}O{{}_7}^{2-}}+H_{2}O$