Some confusion over rate and equilibrium constants

[DontTradOnMe]

Hi guys, hopefully you can help clear up this minor issue for me. So I realize that in the rate law for a forward, irreversible reaction, the exponents representing reaction order must be determined experimentally and are unrelated to the stoichiometry. And yet I also read that Keq = Kf/Kr. I'm a little confused because the expression containing the rate constant K is unrelated to stoichiometry, yet it shows up in the equation for Keq which IS related to stoichiometry.

Is this just because the rate law involving experimentally determined reaction order is only for a forward, irreversible reaction, while the Keq formula involves forward and reverse rate constants for reversible reactions, so they are unrelated? Or am I missing something else? Thanks!

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[Lawpy]

See my derivation here

The equation Keq = kf/kr is true for reversible, elementary reactions. In elementary reactions, there is only a single (and thus rate-limiting) step in the reaction mechanism, so the rate law exponents of the forward reaction are the stoichiometric coefficients of the reactants (and the rate law exponents of the reverse reaction are the stoichiometric coefficients of the products).