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kinetics_ap-1

# kinetics_ap-1 - Kinetics 1971D Ethyl iodide reacts with a...

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Kinetics: 1971D Ethyl iodide reacts with a solution of sodium hydroxide to give ethyl alcohol according to the following equation CH 3 CH 2 I + OH - → CH 3 CH 2 OH + I - The reaction is first order with respect to both ethyl iodide and hydroxide ion, and the overall- rate expression for the reaction is as follows Rate = k[CH 3 CH 2 I][ OH - ] What would you do in the laboratory to obtain data to confirm the order in the rate expression for either of the reactants? 1972 2A +2B → C+D The following data about the reaction above were obtained from three experiments: Experiment [A] [B] Initial rate of formation of C (Molarity/min) 1 0.6 0 0.1 5 6.3x 10 -3 2 0.2 0 0.6 0 2.8 x 10 -3 3 0.2 0 0.1 5 7.0x10 -4 a) What is the rate equation for the reaction? b) What is the numerical value of the rate constant k? c) Propose a reaction mechanism for this reaction. 1973 D Some alkyl Halides such as (CH 3 ) 3 CCl, (CH 3 ) 3 CBr and (CH 3 ) 3 CI represented by Rx are believed to react with water according to the following sequence of reactions to produce alcohols: RX → R + + X - Slow reaction R + + H 2 O → ROH + H + Fast reaction

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a) For the hydrolysis of Rx, write a rate expression constant with the reaction sequence above. b) When the alkyl halides RCl, RBr and RI are added to water under the same experimental conditions, the rates are in order RI>RBr>RCl. Construct properly labeled potential energy diagrams that are constituent with the information on the rates of hydrolysis of the three alkyl halides. Assume that the reactions are exothermic. 1974D A measure of the rate of reaction is its half life. One method of determining the half life of a first order reaction is to plot certain appropriate data. Sketch a graph that illustrates the application of such a method. Label each axis with its name and appropriate units and show how the half life can be obtained from the graph. 1975B 2NO (g) + O 2(g) → 2NO 2(g) A rate expression for the reaction above is –d[O 2 ] / dt = k[NO] 2 [O 2 ] ∆H f ° kcal/mol ∆S ° cal/(mol)(K) ∆G f ° kcal/mole NO (g) 21.60 50.34 20.72 O 2(g) 0 49.00 0 NO 2(g) 8.09 57.47 12.39 a) For the reaction above, find the rate constant at 25°C if the initial rate as defined by the equation above is 28 moles per liter-second when the concentration of nitric oxide is 0.20 mole per liter and the concentration of oxygen is 0.10 mole per liter b) Calculate the equilibrium constant for the reaction at 25°C 1976 D Changing the temperature and no other conditions changes the rates of most chemical reactions. Two factors are commonly cites as accounting for the increased rate of chemical reaction as the temperature is increased. State briefly and discuss the two factors. Which of the two is more important? 1977B
2NO (g) + O 2(g) ↔ 2 NO 2(g) For the reaction above, the rate constant at 380°C for the forward reaction is 2.6 x 10 3 liter 2 /mol 2. sec and this reaction is first order in O 2 and second order in NO. The rate constant for the reverse reaction at 380°C is 4.1 liter/mol . sec and this reaction is second order in NO 2 .

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