Question

$C{r}_2{O}_2^{2-}$ ions are in equilibrium with $Cr{O}_4^{2-}$ ions at PH =4. The yellow chromate solution is obtained when.

• A. $p^H$ increases
• B. $p^H$ decreases
• C. Both (a) & (b)
• D. None of these

Answer 1

The correct option is A $p^H$ increases

On adding an alkali (i.e increasing the pH of solutions), the H⁺ ions are used up & according to the law of chemical equilibrium, the reaction proceeds in the forward direction producing yellow chromate solution.
$C{r}_2{O}_7^{2-}+2O{H}^{-}\to 2Cr{O}_4^{2-}+2H_{2}O$