Rate constants and activation energies

Rate laws, rate constants and activation energies used in the reaction-rates unit — classic measurements, and model values where marked.


$\ce{2N2O5(g) -> 4NO2(g) + O2(g)}$	k[N₂O₅]	3.46 × 10⁻⁵	s⁻¹	25	102.9	measured (Daniels & Johnston 1921); Ea from a six-point fit
$\ce{2N2O5(g) -> 4NO2(g) + O2(g)}$	k[N₂O₅]	4.98 × 10⁻⁴	s⁻¹	45	102.9	measured; half-life 23 minutes
$\ce{2NO2(g) -> 2NO(g) + O2(g)}$	k[NO₂]²	0.54	L mol⁻¹ s⁻¹	300	—	textbook value
$\ce{2NO(g) + O2(g) -> 2NO2(g)}$	k[NO]²[O₂]	7090	L² mol⁻² s⁻¹	25	−4.4	IUPAC recommendation; negative apparent activation energy
$\ce{S2O8^2- + 2I- -> 2SO4^2- + I2}$	k[S₂O₈²⁻][I⁻]	0.008	L mol⁻¹ s⁻¹	25	52.0	model value (depends strongly on ionic strength)
$\ce{2H2O2 -> 2H2O + O2}$	uncatalysed	—		—	75.3	activation energy
$\ce{2H2O2 -> 2H2O + O2}$	k[H₂O₂][I⁻]	—		—	56.5	iodide-catalysed
$\ce{2H2O2 -> 2H2O + O2}$	catalase	—		—	8.4	enzyme-catalysed
$\ce{C2H5OH -> CH3CHO}$	k	0.15	g L⁻¹ h⁻¹	37	—	zero-order elimination of blood ethanol (typical value)

k and Ea for the iodine clock are the model values used by this site’s virtual bench; the rest are literature values.

Sources

F. Daniels, E. H. Johnston, J. Am. Chem. Soc. 43, 53–71 (1921).
R. Atkinson et al., Atmos. Chem. Phys. 4, 1461–1738 (2004) (NO + NO + O₂).
Chemistry LibreTexts, “Ea and catalysts” (H₂O₂ activation energies).
A. W. Jones, Forensic Sci. Int. 200, 1–20 (2010) (ethanol elimination, 0.10–0.35 g L⁻¹ h⁻¹).
R. H. Petrucci et al., General Chemistry (NO₂ decomposition at 300 °C).