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A translucent white waxy solid (A) on heating in an inert atmosphere is converted into its allotropic form (B). Allotrope (A) on reacton with very dilute aqueous KOH liberates a highly poisonous gas (C) having rotten fish smell. With excess of chlorine (C) forms (D) which hydrolyses to compound (E). Identify (A) to (E). |
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Answer» Solution :(i) Since a translucent while waxy solid (A), on heating in an inert atmosphere, is converted into its allotrope (B), THEREFORE, (A) is white or yellow phosphorus while (B) is red phosphorus. `underset("White phosphorus")(P_(4)(s)) overset("Heat, inert gas") (rarr) underset("Red phosphorus")(P_(4)(s))` (ii) Since allotrope (A) on boiling with dilute aqueous KOH gives a heghly poisonous gas (C) having ROTTEN fish smell, therefore, it is confirmed that allotrope (A) is while phosphorus and the poisonous gas (C) is phosphine `(PH_(3))` `underset("White phosphorus (A)")(P_(4) (s)) + 3 KOH (aq) + 3H_(2)O(l) overset("Heat") rarr underset("Pot. hypophosphite")(3KH_(2)PO_(2)(aq))+underset("Phosphine (C)")(PH_(3)(g))` (iii) Since phosphine (C) reacts with excess of CHLORINE to form a compound (D) which upon hydrolysis gives compound (E), therefore, (D) MUST be phosphorus pentachloride `(PCl_(5))` and (E) must be phosphoric acid `(H_(3)PO_(4))`. `underset("Phosphine (C)")(PH_(3)(g))+underset(("Excess"))(4Cl_(2)(g))rarr underset("Phosphorus pentachloride (D)")(PCl_(5)(s))+ 3HCl(g)` `underset((D))(PCl_(5)(s))+4H_(2)O(l) rarr underset("Phosphoric acid (E)")(H_(3)PO_(4_(aq))+5 HCl(aq))` Thus, (A) is white phosphorus, (B) is red PHOSPHOROUS, (C) is phosphine `(PH_(3))`. (D) is phosphorus pentachloride `(PCl_(5))` and (E) is phosphoric acid `(H_(3)PO_(4))` |
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