122 midterm II wi06V4 final_key

122 midterm II wi06V4 final_key - Midterm II, Chemistry 122...

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Midterm II, Chemistry 122 Winter 2006 Monday, February 20th 6:30PM - 7:48PM, Dr. H.C. Allen (25 questions; each question worth 7 points) Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A first-order reaction has a rate constant of 0.33 min -1 . It takes __________ min for the reactant concentration to decrease from 0.13 M to 0.088 M. A) 0.85 B) 1.4 C) 0.51 D) 0.13 E) 1.2 A flask is charged with 0.124 mol of A and allowed to react to form B according to the reaction A(g) ¬B(g). The following data are obtained for [A] as the reaction proceeds: Time (s) 1 10 20 30 40 Moles of A 0.124 0.110 0.088 0.073 0.054 2) The average rate of disappearance of A between 10 s and 20 s is __________ mol/s. A) 9.90 ˛ 10 -3 B) 2.2 ˛ 10 -3 C) 454 D) 4.4 ˛ 10 -3 E) 1.1 ˛ 10 -3 3) The rate constant for a second-order reaction is 0.13 M -1 s -1 . If the initial concentration of reactant is 0.26 mol/L, it takes __________ s for the concentration to decrease to 0.13 mol/L. A) 1.0 B) 0.50 C) 0.017 D) 4.4 x 10 -3 E) 30 4) The rate constant of a first-order process that has a half-life of 225 s is __________ s -1 . A) 12.5 B) 0.693 C) 3.08 x 10 -3 D) 1.25 E) 4.44 x 10 -3 5) A second-order reaction has a half-life of 18 s when the initial concentration of reactant is 0.71 M. The rate constant for this reaction is __________ M -1 s -1 . A) 1.3 B) 3.8 x 10 -2 C) 7.8 x 10 -2 D) 2.0 x 10 -2 E) 18 The peroxydisulfate ion (S 2 O 8 2- ) reacts with the iodide ion in aqueous solution via the reaction: S 2 O 8 2- (aq) + 3I - ¬ 2SO 4 (aq) + I 3 - (aq) An aqueous solution containing 0.050 M of S 2 O 8 2- i on and 0.072 M of I - is prepared, and the progress of the reaction followed by measuring [I - ]. The data obtained is given in the table below. Time (s)
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122 midterm II wi06V4 final_key - Midterm II, Chemistry 122...

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