Write me a rate expression. You know how to do it for single equaions, right?

Well I've never seen it before so I'm probably wrong but I'll give it a shot.

If it were just 3A

C rate equation is:

[tex]

\frac{dc_A}{dt}=-k_{1f} \cdot (c_A)^x + \frac{1}{3} k_{1r} \cdot (c_C)^n \\

[/tex]

So in the case of aA + bB

cC + dD, I might suggest:

[tex]

\frac{dc_A}{dt}=-\frac{b}{a} k_{1f} \cdot (c_A)^x \cdot (c_B)^y + \frac{c}{a} \frac{d}{a} k_{1r} \cdot (c_C)^n \cdot (c_D)^m \\

[/tex]

x is the order with respect to A, y with respect to B, n with respect to C, m with respect to D; a, b, c, d are the stoichiometric coefficients on A to D respectively.