In the reaction: P 2 H 4 ⟶ P H 3 + P 4 H 2 the equivalent mass of P₂H₄ may be given as: (M = M.wt of P₂H₄)

Question

In the reaction: P 2 ​ H 4 ​ ⟶ P H 3 ​ + P 4 ​ H 2 ​ the equivalent mass of P₂H₄ may be given as: (M = M.wt of P₂H₄)

TestHub · Accepted Answer

Explain the Question: Find the equivalent mass ( $E$ ) of P₂H₄ in the reaction: P₂H₄ → PH₃ + P₄H₂.

Concept: This question is based on disproportionation, where $E = M / n_{n e t}$ , and $n_{n e t} = \frac{n _{1} \times n _{2}}{n _{1} + n _{2}}$ .

Solution:

1. Oxidation states of P: P₂H₄ (–2), PH₃ (–3), P₄H₂ (–0.5).

2. Half-reaction n-factor (per mole of P₂H₄ with 2 P atoms):

Reduction ( $n_{1}$ ): $2 \times ∣ - 3 - (- 2) ∣ = 2$

Oxidation ( $n_{2}$ ): $2 \times ∣ - 0.5 - (- 2) ∣ = 3$

$n_{n e t} = \frac{2 \times 3}{2 + 3} = \frac{6}{5}$

$E = M / \frac{6}{5} = \frac{5 M}{6}$

Final answer: B

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