The reaction 4 HBr(g) + O2(g) --> 2 H2O(g) + 2 Br2(g) proceeds through the following mechanism:

HBr(g) + O2(g) --> HOOBr(g)

HOOBr(g) + HBr(g) --> 2 HOBr(g)

HOBr(g) + HBr(g) --> Br2(g) + H2O(g)

(a) The first step of this mechanism is rate-determining (slow). What is the rate law for this reaction?

(b) What would the rate law be if the second step of this mechanism were rate-determining?