Cheat Sheet — INC-03 Final Revision — Notes

INC-03 — Final Cheat Sheet (Groups 16-18)

Contact Process (H2SO4 manufacture)

Step	Reaction	Conditions
1	$\text{S} + \text{O}_2 \rightarrow \text{SO}_2$	Air combustion
2	$2\text{SO}_2 + \text{O}_2 \rightleftharpoons 2\text{SO}_3$	V2O5, 450°C ← MEMORIZE
3	$\text{SO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{H}_2\text{S}_2\text{O}_7$	Absorption tower → OLEUM
4	$\text{H}_2\text{S}_2\text{O}_7 + \text{H}_2\text{O} \rightarrow 2\text{H}_2\text{SO}_4$	Dilution

TRAP: SO3 NOT dissolved in water (acid mist) → dissolved in conc. H2SO4 (oleum)

Xenon Compounds (NEET Favorite)

Compound	Hybridization	Geometry	Lone Pairs	Hydrolysis
XeF2	sp3d	Linear	3 (equatorial)	Xe + 2HF + ½O2
XeF4	sp3d2	Square planar	2 (trans axial)	Disproportionation → Xe + XeO3 + HF
XeF6	sp3d3	Distorted octahedral	1	XeO3 + 6HF (XeO3 = explosive)

Halogen Oxoacids of Chlorine

$\underbrace{\text{HOCl}}_{+1, \text{ weakest}} < \underbrace{\text{HClO}_2}_{+3} < \underbrace{\text{HClO}_3}_{+5} < \underbrace{\text{HClO}_4}_{+7, \text{ strongest}}$ Rule: More O atoms → stronger acid | Fluorine: NO oxoacids (no d-orbitals)

Interhalogen Shapes

Type	Example	Shape	Lone pairs
AB	ClF, ICl	Linear	3
AB3	ClF3, BrF3	T-shaped	2
AB5	BrF5, IF5	Square pyramidal	1
AB7	IF7	Pentagonal bipyramidal	0

HX Key Facts

Acidic strength: HF < HCl < HBr < HI
Thermal stability: HF > HCl > HBr > HI
Oxidizing power of X2: F2 > Cl2 > Br2 > I2
HF is weak acid: H-F bond = 568 kJ/mol (strongest H-X bond) + H-bonding

Other Key Reactions

$\text{Ca(OH)}_2 + \text{Cl}_2 \rightarrow \underbrace{\text{CaOCl}_2}_{\text{bleaching powder}} + \text{H}_2\text{O}$ $\text{O}_3 + 2\text{KI} + \text{H}_2\text{O} \rightarrow 2\text{KOH} + \text{O}_2 + \underbrace{\text{I}_2}_{\text{blue-black with starch}}$ $\text{XeF}_6 + 3\text{H}_2\text{O} \rightarrow \underbrace{\text{XeO}_3}_{\text{explosive}} + 6\text{HF}$

Sulfur Allotropes

Rhombic (α-sulfur): Stable below 95.6°C, S8 rings, orthorhombic crystal
Monoclinic (β-sulfur): Stable 95.6°C–119°C, S8 rings, monoclinic crystal
Transition temperature: 95.6°C ← MEMORIZE