[mana]

hi all
when we try to write a rate formula, we have to know the order of reaction, and there is no relationship between reaction order and the stoichiometric coefficients but when we try to write the equilibrium equation, we use the stoichiometric coefficients, I can't understand why? for example at the following reaction, why we use stoichiometric coefficients for writing the equations?
N2O4  2NO2
ratefwd = raterev
 kfwd[N₂O₄]eq = krev[NO₂]² 
K =kfwd/krev= [NO₂]_eq ²/ [N₂O₄]eq

[Borek]

Broadly speaking kinetics and equilibrium are two different things, so there are different rules governing them.