In the balanced chemical equation for the disproportionation of white phosphorus () in an alkaline m — Electrochemistry Chemistry Question
Question
In the balanced chemical equation for the disproportionation of white phosphorus ($P_4$) in an alkaline medium: $P_4 + 3OH^- + 3H_2O \rightarrow PH_3 + 3H_2PO_2^-$, the equivalent weight of $P_4$ is $M/x$, where $M$ is the molar mass of $P_4$. What is the exact integer value of $x$?
Answer: 3
💡 Solution & Explanation
In this disproportionation, $P_4$ ($0$) oxidizes to $H_2PO_2^-$ ($+1$) and reduces to $PH_3$ ($-3$). For oxidation: $n_1 = 4 \times 1 = 4$. For reduction: $n_2 = 4 \times 3 = 12$. The net n-factor for the disproportionating species is $\frac{n_1 \times n_2}{n_1 + n_2} = \frac{4 \times 12}{4 + 12} = \frac{48}{16} = 3$. Therefore, Equivalent weight = $M/3$, making $x = 3$.
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