Question

Consider reversible reaction,
$ HCN(aq)H^{+}(aq)+CN^{-}(aq) $
At equilibrium the addition of $ CN^{-}(aq) $ would

• A. decrease the $ H^{+}(aq) $ ion concentration
• B. reduce HCN (aq) concentration
• C. increase the equilibrium constant
• D. decrease the equilibrium constant

Answer 1

Answer: (A)

For the reaction
$HCN (a q) \rightleftharpoons H ^{+}(a q)+ CN ^{-}(a q) $
$K_{c}=\frac{\left[ H ^{+}\right]\left[ CN ^{-}\right]}{[ HCN ]}$
On the addition of $CN ^{-}(a q)$ at equilibrium, the $\left[ H ^{+}\right]( aq )$ decrease to maintain the equilibrium constant.