Question

Determine and report the rate law for the reaction of iodide and persul fate ions. Show all calculations and justifications. 2 3.Based on the rate law that you determined above, calculate the values and units of k for: a. the three initial rates experiments in Part A, b. the one initial rates experiment at a different temperature in Part B. 4Use your two experiments done at different temperatures to determine the activation energy Ea and the Arrhenius pre-exponential factor A SA proposed mechanism for the reaction of iodide and persul fate ions is: Step 1: I'(aq) +S,0, (aq) S,0, r(aq) Step 2: [S,O, I (aq) + I(aq) L (aq) + 2 SO (aq) Use the steady state approximation to determine the rate law that corresponds to the proposed reaction mechanism. Sketch the reaction profile diagram for this mechanism. Given the experimental rate law that you have determined in this experiment, what can you say about relative values of k-1, and k2 in the proposed reaction mechanism? 6 7 Sketch the Lewis structures of the reactants and products. Using the proposed mechanism, sketch the orientations of the molecules necessary for each elementary step. Justify the orientations. Once finished the questions in your lab notebook and you have cleaned up your bench, your TA

Question 5 and 6

Answer 1

KI Guren, the mechanism is Step 1 I-lag) + Sulg 2- (aq) // [S₂ g 1] (aq) Step 2 [$2081109) + I-(aq) k2, I, (09) + 25042-(aq) The rate haue is given as more rate laws - kg x [11] * [S208 15"Q). we need to apply insteady state principle to find out the concentration g [ S20g IJS-- we know that the conc. of [5₂08 I] 3 - does not change during the reaction i.e. it remains so, d[52081].... steady po - dt see → from step 1, we d [S2031) dt k[ 1 ][ 9,032-] - K-1 [S2015] - C). K-1 .. Substituting rate [S20I 3-] = ki[14][,082-3 CI) In ), we get → lav = kqx [I -72 x [ Se Og 2-] x ki K-1

given as followers Reaction profile diagram is Step-I step-II Energy ? Inte radiate Reactants Products ter Reaction co-ordinate. 10] 6. As the product via value of kg the reaction have let to reaction proceeds towards the final Step-I, we can say that the should be greater than kal, otherwise would not have proceeded, it would formation of the initial reactants. L T -10.27