Contact Process

$\text{S} + \text{O}_2 \rightarrow \text{SO}_2$ $2\text{SO}_2 + \text{O}_2 \underset{450°C}{\overset{\text{V}_2\text{O}_5}{\rightleftharpoons}} 2\text{SO}_3$ $\text{SO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{H}_2\text{S}_2\text{O}_7 \text{ (oleum)}$ $\text{H}_2\text{S}_2\text{O}_7 + \text{H}_2\text{O} \rightarrow 2\text{H}_2\text{SO}_4$

H2SO4 as Oxidizing Agent (Hot, Conc.)

$\text{Cu} + 2\text{H}_2\text{SO}_4\text{(hot, conc.)} \rightarrow \text{CuSO}_4 + \text{SO}_2\uparrow + 2\text{H}_2\text{O}$ $\text{S} + 2\text{H}_2\text{SO}_4\text{(hot, conc.)} \rightarrow 3\text{SO}_2 + 2\text{H}_2\text{O}$

H2SO4 as Dehydrating Agent

$\text{C}_{12}\text{H}_{22}\text{O}_{11} \xrightarrow{\text{H}_2\text{SO}_4} 12\text{C} + 11\text{H}_2\text{O} \text{ (charring of sugar)}$ $\text{HCOOH} \xrightarrow{\text{H}_2\text{SO}_4} \text{CO} + \text{H}_2\text{O}$

Ozone Reactions

$3\text{O}_2 \xrightarrow{\text{silent electric discharge}} 2\text{O}_3$ $\text{O}_3 + 2\text{KI} + \text{H}_2\text{O} \rightarrow 2\text{KOH} + \text{O}_2 + \text{I}_2 \text{ (KI-starch test, blue-black)}$ $\text{O}_3 \rightarrow \text{O}_2 + [\text{O}] \text{ (nascent oxygen — oxidizing action)}$ $\text{PbS} + 4\text{O}_3 \rightarrow \text{PbSO}_4 + 4\text{O}_2 \text{ (black → white)}$

Xenon Hydrolysis

$\text{XeF}_2 + \text{H}_2\text{O} \rightarrow \text{Xe} + 2\text{HF} + \tfrac{1}{2}\text{O}_2$ $6\text{XeF}_4 + 12\text{H}_2\text{O} \rightarrow 4\text{Xe} + 2\text{XeO}_3 + 24\text{HF} + 3\text{O}_2 \text{ (disproportionation)}$ $\text{XeF}_6 + 3\text{H}_2\text{O} \rightarrow \text{XeO}_3 + 6\text{HF} \text{ (XeO}_3\text{ is explosive)}$

Halogen Reactions

$\text{Ca(OH)}_2 + \text{Cl}_2 \rightarrow \text{CaOCl}_2 + \text{H}_2\text{O} \text{ (bleaching powder)}$ $4\text{HF} + \text{SiO}_2 \rightarrow \text{SiF}_4\uparrow + 2\text{H}_2\text{O} \text{ (glass etching)}$ $\text{Cl}_2 + 2\text{KBr} \rightarrow 2\text{KCl} + \text{Br}_2 \text{ (halogen displacement)}$