CHEM 178Tuesday, February 05, 8:10-9:001. The elementary steps of are proposed to be A + B ABAB + B AB2 a) What is the overall reaction?A + 2B AB2b) If the Rate law is determined to be Rate = k[A][B] , what is the rate determining step?Step 1: A + B AB2. Given the following rate law, what is a plausible reaction mechanism? Rate =k[A]2[B] a) 2A + B A2BNO. This reaction is termolecular which is highly unlikely. b) A + B AB (fast and reversible) AB + B AB2 (slow)NO. The Rate law = k[A][B]2 c) A+B AB (fast and reversible) AB+A A2B (slow)Yes. d) A+B AB (slow) AB+A A2B (fast and reversible)NO. Rate = k[A][B] 3. In the reaction A+2B AB2 , the intermediate AB is formed. Propose a mechanism for the reaction if the Rate law is determined to be Rate=k[A][B]2. (Label the rate determining step)First, form the intermediateA + B ABThen, use the intermediate and remaining reactants.AB + B AB2Check that the elementary steps add up to the original overall reaction. The Rate law of step 1 is Rate = k[A][B] --this is not the observed rate law.The Rate law of step 2 is Rate = k[AB][B]. NOTE: IF the second step is a slow step, the first step will be an equilibrium step. AB is an intermediate so we need to use the first reaction to substitute. Ratef = kf[A][B] = Rater = kr[AB] (In an equilibrium reaction, Ratef = Rater). Solving for [AB] we get [AB] = kf[A][B]/ kr. Plug in this into the Rate Law. Rate = k (kf[A][B]/ kr)[B]. Simplifying and combining all the k values into one k, we get Rate=k[A][B]2. This matches our observed Rate law, so our proposed mechanismworks.4. What are the rate laws of the reversible reaction N2 + 3H2 2NH3 ?Ratef = kf[N2][ H2]3 = Rater =
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