Which of the following is not a disproportionation reaction? o I. NH NO N O 2H O II.P 3NaOH 3H O P H — Redox Reactions and Volumetric Analysis Chemistry Question

💡 Solution & Explanation

# Solution: Identifying Non-Disproportionation Reactions A **disproportionation reaction** occurs when a single element simultaneously undergoes both oxidation AND reduction (changing to higher and lower oxidation states). Let me analyze each reaction: ## **I. $2NH_2NO_3 \rightarrow N_2O + 2H_2O$** - N in $NH_2NO_3$: one N is –3 (in $NH_2$), one N is +5 (in $NO_3^-$) - Products: N in $N_2O$ is +1 - One N goes from –3 to +1 (oxidation), other from +5 to +1 (reduction) - ✓ **Disproportionation** ## **II. $P_4 + 3NaOH + 3H_2O \rightarrow PH_3 + 3NaH_2PO_2$** - P in $P_4$: 0 (elemental) - Products: P in $PH_3$ is –3, P in $NaH_2PO_2$ is +1 - One P goes from 0 to –3 (reduction), other from 0 to +1 (oxidation) - ✓ **Disproportionation** ## **III. $PCl_5 \rightarrow PCl_3 + Cl_2$** - P remains in +5 state (in both $PCl_5$ and $PCl_3$) - Cl in $PCl_5$: –1 → some Cl in $PCl_3$: –1, some in $Cl_2$: 0 - Only Cl undergoes redox, not P. P does not change oxidation state. - ✗ **NOT a disproportionation of a single element** ## **IV. $2IO^- + H_2O \rightarrow I^- + IO_3^- + 2H^+$** - I in