Hi, I'm working on this problem for PChem and am getting some rather hairy answers!

Work:

The rate of the reaction should be: [tex]R = \frac{-d[RH]}{dt} = \frac{-d[Br_{2}]}{dt} = \frac{d[RBr]}{dt} = \frac{d[HBr]}{dt}[/tex]

I used the steady-state approximation to solve for: [tex]0 = \frac {d(Br)}{dt} = 2k_{1}Br_{2} - k_{2}BrRH + k_{2}RBr_{2} - k_{4}BrR[/tex] and [tex]\frac{d(R)}{dt} = 0 = k_{2}*Br*RH - k_{3}*R*Br_{2} - k_{4}*Br*R[/tex]

And eventually got: [tex][R] = \frac{[ B][RH]k_2 - [Br_2]k_1}{[Br2]k_3}[/tex] and [tex]

= \frac{[Br2]([R]k_3 + k_1)}{[RH]k_2}[/tex]

However, when I go on to plug these back into the SS equations (to get [R] and [ Br] in terms of [RH] and [Br_{2}] only), I get some pretty nasty-looking stuff and end up with a crazy-looking quadratic. Am I approaching the problem wrong?