Net ionic equation:
C₁₈H₂₁O₃N(aq) + H₂O(l) ⇄ C₁₈H₂₁O₃NH⁺(aq) + OH⁻(aq).
According to Bronsted-Lowry theory acid are donor of protons and bases are acceptors of protons (the hydrogen cation or H⁺).
Codeine (C₁₈H₂₁O₃N) is Bronsted base and it can accept proton and become conjugate acid (C₁₈H₂₁O₃NH⁺).
pKb for codeine is 5.8.
