9.4 Carbon and Phosphorus

Unit 9.4: Carbon and Phosphorus (3 Teaching Hours)

1. Carbon

   • Allotropes of Carbon (Crystalline and Amorphous) Including Fullerenes
     • Crystalline Allotropes: Diamond (tetrahedral, sp³, hard, insulator), Graphite (layered, sp², soft, conductor), Fullerenes (e.g., C₆₀, cage-like, sp²).
     • Amorphous Allotropes: Coal, charcoal, coke (disordered carbon structures, used as fuels or adsorbents).
     • Fullerenes: Structure (spherical, tubular, e.g., C₆₀ buckyball); Properties (high stability, electron acceptor); Uses (nanotechnology, drug delivery, superconductors).
     • Figure 1: Structures of Carbon Allotropes (Diagram showing diamond, graphite, and fullerene structures).
   • Properties of Carbon Monoxide (CO)
     • Reducing Action: Strong reducing agent, reduces metal oxides to metals: Fe₂O₃ + 3CO → 2Fe + 3CO₂.
     • Reaction with Metals: Forms metal carbonyls (e.g., Ni(CO)₄ with nickel).
     • Reaction with Non-Metals: Reacts with Cl₂ to form phosgene: CO + Cl₂ → COCl₂.
     • Figure 2: Structure of Carbon Monoxide (Diagram showing CO triple bond structure).
   • Uses of Carbon Monoxide
     • Reducing agent in metallurgy (e.g., iron extraction).
     • Fuel in producer gas and water gas.
     • Synthesis of organic compounds (e.g., methanol).

2. Phosphorus

   • Allotropes of Phosphorus (Name Only)
     • White Phosphorus, Red Phosphorus, Black Phosphorus.
   • Preparation of Phosphine (PH₃)
     • No diagrams or descriptions required as per curriculum.
     • Prepared by heating white phosphorus with conc. NaOH: P₄ + 3NaOH + 3H₂O → PH₃ + 3NaH₂PO₂.
   • Properties of Phosphine (PH₃)
     • Basic Nature: Weak base, forms phosphonium salts with strong acids: PH₃ + HBr → PH₄Br.
     • Reducing Nature: Strong reducing agent, reduces AgNO₃ to silver: PH₃ + 6AgNO₃ → 6Ag + H₃PO₃ + 3HNO₃.
     • Action with Halogens: Reacts to form phosphorus halides: PH₃ + 4Cl₂ → PCl₅ + 3HCl.
     • Action with Oxygen: Burns to form phosphorus pentoxide: 2PH₃ + 4O₂ → P₂O₅ + 3H₂O.
     • Figure 3: Structure of Phosphine (Diagram showing trigonal pyramidal structure of PH₃).
   • Uses of Phosphine
     • Synthesis of organophosphorus compounds.
     • Fumigant in pest control.
     • Used in semiconductor industry (doping).