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APEX CLASS ESTD 2018

IITJEE CHEMISTRY: Metallurgy & p-Block Elements Visualizer

By

Ashish Kumar Bahekar

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APEX CLASS • IITJEE Inorganic Chemistry Lab

Metallurgy & p-Block Elements Visualizer

Master Ellingham Diagrams, Vapor Phase Refining, Inert Pair Effect, and Xenon VSEPR Shapes!

🔬 Select a Metallurgical Process to Visualize:
ΔG° Temperature (T) → 0 2M + O₂ → 2MO (ΔS < 0) 2C + O₂ → 2CO (ΔS > 0) T (Threshold) Ellingham Diagram: ΔG° vs T • Plots ΔG° of formation of oxides vs T. • Most metals slope UP: ΔS < 0 (Consuming O₂). • Carbon to CO slopes DOWN: ΔS > 0. 🏆 Golden Rule of Reduction: Above Threshold T, Carbon line is LOWER. C can reduce the oxide of ANY metal above it! Air Supply Sulfide Ore in Froth Hydrophilic Gangue Froth Floatation Process (For Sulfide Ores) • Principle: Preferential wetting of ore by oil & gangue by water. • Collectors (Pine Oil, Xanthates): Enhance non-wettability of ore. • Froth Stabilizers (Cresol, Aniline): Stabilize the froth. 🚨 JEE Depressant Trap (NaCN): Used to separate ZnS and PbS. NaCN selectively forms a soluble complex Na₂[Zn(CN)₄] with ZnS, allowing PbS to froth! 1. Smelting (Carbon Reduction) Used for: Fe, Zn, Sn, Pb ZnO + C → Zn + CO Fe₂O₃ + 3CO → 2Fe + 3CO₂ Flux + Gangue = Slag (e.g., CaO + SiO₂ → CaSiO₃) 2. Auto-Reduction (Self-Reduction) Used for less electropositive metals: Cu, Pb, Hg (No external reducing agent required!) Cu₂S + 2Cu₂O → 6Cu + SO₂ ↑ Produces “Blister Copper” (Blisters are caused by escaping SO₂ gas!) Ultrapure Refining: Vapor Phase & Zone Refining 1. Vapor Phase Refining Form a volatile compound, then decompose it. • Mond Process (For Nickel): Ni(impure) + 4CO → Ni(CO)₄ → Ni(pure) + 4CO • Van Arkel Method (For Ti / Zr): Zr(impure) + 2I₂ → ZrI₄ → Zr(pure) + 2I₂ 2. Zone Refining (Fractional Crystallization) For Semiconductors (Si, Ge, Ga) – Ultra high purity. Moving Heater → Principle: Impurities are MORE soluble in the MELT than in the solid state!
MacArthur Forrest Cyanide
Leaching of Ag and Au
Complex: [Ag(CN)₂]⁻. Zinc used to displace.
Hall-Heroult Process
Al₂O₃ Electrolysis
Cryolite (Na₃AlF₆) added to lower MP & inc. conductivity.
Calcination vs Roasting
No Air vs Excess Air
Carbonates (Calcination) | Sulfides (Roasting)
Matte (Copper Smelting)
Cu₂S + FeS
Formed in reverberatory furnace before Bessemer.
🧪 Select a p-Block Concept to Visualize:
The Inert Pair Effect (Reluctance of ns² electrons to bond) Group 13 (ns² np¹) Al: +3 stable Ga: +3 stable In: +3 > +1 Tl: +1 > +3 Group 14 (ns² np²) Si: +4 stable Ge: +4 > +2 Sn: +4 > +2 Pb: +2 > +4 Group 15 (ns² np³) P: +5 stable As: +5 stable Sb: +5 > +3 Bi: +3 > +5 Stability of Lower O.S. Increases 1. Phosphorus Oxoacids (Basicity depends ONLY on P-OH bonds!) H₃PO₄ (Tribasic) P O OH OH OH 3 × P-OH H₃PO₃ (Dibasic) P O OH OH H 2 × P-OH, 1 × P-H H₃PO₂ (Monobasic) P O OH H H 1 × P-OH, 2 × P-H 2. Sulfur Oxoacids H₂SO₄ (Sulfuric Acid) 2 × S=O, 2 × S-OH (Dibasic) H₂S₂O₇ (Oleum / Pyrosulfuric) Has S-O-S bridge! H₂S₂O₈ (Marshall’s Acid) Has Peroxide S-O-O-S linkage! Noble Gas Compounds: Xenon Fluorides VSEPR Shapes XeF₂ (2 BP + 3 LP = 5) sp³d (Linear) Xe F F •• •• •• XeF₄ (4 BP + 2 LP = 6) sp³d² (Square Planar) Xe FF FF •• •• XeF₆ (6 BP + 1 LP = 7) sp³d³ (Distorted Octahedral) Xe F F F F F F •• 1. Silicates (SiO₄⁴⁻ building blocks) Si Ortho-silicate (Discrete) • Pyrosilicate: 1 O shared • Chain/Ring: 2 O shared • Sheet: 3 O shared • 3D Network: 4 O shared 2. Silicones (Polymeric Organosilicon) Repeating unit: (R₂SiO)n. Formed by hydrolysis of R₂SiCl₂. RR – Si – O –Si – O – RR Highly water repellent (hydrophobic alkyl groups)!
Boric Acid (H₃BO₃)
Lewis Acid (Not Arrhenius)
Accepts OH⁻ from water. Monobasic!
Nitrogen Oxides Trap
NO & N₂O are Neutral!
N₂O₃, NO₂, N₂O₅ are Acidic.
Interhalogens (XX’ₙ)
More reactive than Halogens
X-X’ bond is weaker than X-X bond.
Contact Process (H₂SO₄)
Catalyst: V₂O₅
SO₂ + ½O₂ → SO₃ is the key step.
🔥 High-Yield JEE Xe Compound Trap:
Hydrolysis of Xenon Fluorides: Partial hydrolysis of XeF₆ gives XeOF₄ + 2HF (replaces 2 F with 1 O). Further hydrolysis gives XeO₂F₂, and complete hydrolysis gives highly explosive XeO₃! (Notice the oxidation state of Xe remains +6 throughout all these reactions!)
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