Question

Given the following reaction at equilibrium: $F{e}^{3+}\left(aq\right)+SCN\leftrightharpoons FeSC{N}^{2+}\left(aq\right)$. Find the one among the following which results in shifting the equilibrium to the left.

• A. adding $FeC{l}_3$ to the reaction
• B. adding $N{H}_{4}SCN$ to the reaction
• C. increasing the pressure on the reaction
• D. adding a catalyst
• E. adding $FeSC{N}^{2+}\left(aq\right)$ to the reaction

Answer 1

The correct option is E adding $FeSC{N}^{2+}\left(aq\right)$ to the reaction

The given reaction is:-

${Fe}^{+}\left(aq\right)+{SCN}^{-}\rightleftharpoons {\left[Fe\left(SCN\right)\right]}^{2+}\left(aq\right)$

When ${\left[Fe\left(SCN\right)\right]}^{2+}$ is added to the reaction at equilibrium, by le chatelier's principle, to compensate the increase, backward reaction takes place. So, equilibrium shifts to left.