[DutchGirl13]

For my PChem class, I have to write reaction rates in terms of the disappearance of reactant and appearance of product. Here are the reactions:
a). 3O₂ 2O₃
b). C₂H₆ C₂H₄+H₂
c). ClO^-+Br^- BrO^-+Cl^-
d).(CH₃)₃CCl+ H₂O (CH₃)₃COH + H⁺ + Cl^-
e). 2AsH₃ 2As + 3H₂

These are my tentative answers:
a). rate= -3k₁[O₂]³/sub] + 2k_-1[O₃]³
b). rate= -k₁[C₂H₆]+k_-1[C₂H₄][H₂]
c). rate= -k₁[ClO^-][Br^-]+k_-1[BrO^-][Cl^-]
d). rate= -k₁[(CH₃)₃CCl][H₂O]+k_-1[(CH₃)₃COH] [H⁺][Cl^-]
e). rate= -2k₁[AsH₃]²+k_-1[H₂]³[As]²

Would someone please offer guidance to me on how to write rate laws in this fashion? Where does water belong in a rate law? When do I need to use coefficients, and when do I need to use exponents? Part e) is especially thorny on this.  Where can I find some more practice problems of this sort and ones where I have find the differential amount of a reactant or product?

Thanks for any help you can offer. I want to understand this general concept, not just solve these problems. If this is in the wrong forum, please move it.

[juanrga]

Start from considering

aA   bB

$$ rate = - \frac{1}{a} \frac{d[A]}{dt} = \frac{1}{b} \frac{d[ B]}{dt} /$$

I do not understand your other questions.

[faizan]

first make it clear that either u want to write rate of these reactions or rate expressions for these reactions?