Common Reactions by Order: Reference Table

Reaction	Condition	Reason for Zero Order
$2NH_{3}$ → $N_{2}$ + $3H_{2}$	Pt surface, high pressure	Surface saturation
Many enzyme-catalyzed	High [substrate]	Enzyme saturation (Michaelis-Menten)
Photochemical reactions	Fixed light intensity	Rate depends on photon flux, not [reactant]

Reaction	SMILES	Notes
Radioactive decay (any)	—	Nuclear process, always first order
$H_{2}O_{2}$ decomposition	OO	2 $H_{2}O_{2}$ → $2H_{2}O$ + $O_{2}$
$N_{2}$$O_{5}$ decomposition	—	2 $N_{2}$$O_{5}$ → 4N $O_{2}$ + $O_{2}$
Ethyl acetate hydrolysis (excess $H_{2}O$ )	CC(=O)OCC	Pseudo first-order

Reaction	Order	Notes
$H_{2}$ + $Br_{2}$ → 2HBr	3/2	Chain mechanism: rate = k[ $H_{2}$ ][ $Br_{2}$ ]^(1/2)
$NH_{3}$ decomposition on W	~1	Pressure-dependent