Cl + O3 ---> ClO + O2O + ClO ---> Cl + O2= O + O3 ----> 2O2What is the catalyst? The intermediate?How do you know which is which? If the rate law is rate=k [O3] [Cl]determine:a) the overall order.b) unit for k.c) the rate determining step, justify your answer.
Cl is the catalyst. ClO the intermediate. The catalyst is the component which does not change in overall reaction. He forms some intermediate component(s) with the reactants. In the later reaction steps the intermediate(s) react forming the catalyst in its original state. (a) The overall order is the sum of the orders with respect to the components: n = 1 +1 = 2 (b) the unit of the rate of reaction is r [=] mol/ (Ls) (more general mol per unit time and volume) compare dimensions mol / (Ls) [=] k · mo/L · mol/L =k [=] L/(s mol) (more general unit volume per unit time and mole) (c) First reaction For elementary reaction steps the order of the reaction rate with respect to a reactant is equal to stoichiometric coefficient. Hence the rate of first reaction is: r? = k?·[Cl]·[O?] Overall rate is given by the rate determining step, while other reaction steps are in equilibrium: r = r? = k?·[Cl]·[O?] If second reaction is the rate determine step r? = k?·[O]·[ClO] while reaction 1 is at equilibrium K? = ( [ClO]·[O?] ) / ( [Cl]·[O?] ) =[ClO] = K?·( [Cl]·[O?] ) / [O?] the overall rate would be: r = r? = k?·[O]·[ClO] = K?·k?·[O]·[Cl]·[O?] / [O?] = k·[O]·[Cl]·[O?] / [O?] That doesn't match the observed rate law
