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Intext · Q8

Q.What happens when white phosphorus is heated with concentrated NaOH solution in an inert atmosphere of CO2 ?

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Step 1 — The reaction.

White phosphorus, when boiled with concentrated NaOH solution, undergoes disproportionation:

P4+3NaOH+3H2O→PH3↑+3NaH2PO2P_4 + 3NaOH + 3H_2O \rightarrow PH_3\uparrow + 3NaH_2PO_2

Step 2 — Oxidation state analysis.

Elemental P4P_4 has phosphorus at 0. In the products, phosphorus is simultaneously:

0→−3  (in PH3,reduction)0 \rightarrow -3 \; (\text{in } PH_3, \text{reduction})

0→+1  (in NaH2PO2, sodium hypophosphite, oxidation)0 \rightarrow +1 \; (\text{in } NaH_2PO_2, \text{ sodium hypophosphite, oxidation})

confirming this is a disproportionation reaction.

Step 3 — Why an inert CO₂ atmosphere is needed. …

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