Answer
$CN^-$ acts as a weak base in solution.
- $CN^-(aq) + H_2O(l) \lt -- \gt HCN(aq) + OH^-(aq)$
Work Step by Step
1. Protonate this anion, to get its conjugate acid:
$CN^- --\gt HCN$
2. Analyze the protonated compound.
- Weak acids have weak bases as conjugate pair.
- HCN is a weak acid, therefore, $CN^-$ acts as a weak base.
3. Now that we know that, write the equation where $CN^-$ receives a proton from a water molecule, producing $OH^-$
- $CN^-(aq) + H_2O(l) \lt -- \gt HCN(aq) + OH^-(aq)$
