Chlorine Disproportionation with NaOH

Chemical Redox Equations:

$$\begin{aligned} \text{Cold \& Dilute NaOH:} &\quad \text{Cl}_2 + 2\text{NaOH} \longrightarrow \text{NaCl} + \text{NaOCl} + \text{H}_2\text{O} \\ \text{Hot \& Concentrated NaOH:} &\quad 3\text{Cl}_2 + 6\text{NaOH} \longrightarrow 5\text{NaCl} + \text{NaClO}_3 + 3\text{H}_2\text{O} \end{aligned}$$

Concept: Chlorine undergoes simultaneous oxidation and reduction (disproportionation) in alkaline media, where temperature and alkali concentration dictate whether hypochlorite or chlorate is produced.

Notation:

• $$\text{NaOCl}$$ = Sodium hypochlorite (Chlorine at $$+1$$ state);
• $$\text{NaClO}_3$$ = Sodium chlorate (Chlorine at $$+5$$ state);
• $$\text{NaCl}$$ = Sodium chloride (Chlorine at $$-1$$ state).