Q2ans - Full credit for either) 3. A reaction mechanism is...

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Chem 112 Quiz # 2 1/29/07 1. The reaction of fluorine with chlorine dioxide was studied at 250K: F 2 + ClO 2 products. The following rates were determined. rate [F 2 ] 0 [ClO 2 ] 0 0.0012 M s -1 0.10M 0.010M 0.0024 0.10 0.020 0.0024 0.20 0.010 Find the rate law and the value of the rate constant. By inspection, the reaction is first-order with respect to each reactant. Overall rate law: rate = k[F 2 ][ClO 2 ] 0.0012M s -1 = k (0.10M)(0.010M) k = 1.2 M -1 s -1 2. The reaction 2OF 2 2F 2 + O 2 was studied at 250 0 C by monitoring [OF 2 ] vs. time. The graph of 1/[OF 2 ] vs time was linear with a slope of 1.39 × 10 -2 M -1 s -1 . What is the rate law? What is the value of the rate constant? Since the slope of 1/conc vs time is linear, you know the reaction is second order. The rate constant equals the slope (well, technically, 2k = slope.
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Unformatted text preview: Full credit for either) 3. A reaction mechanism is proposed as follows: Tl + + Co +3 Tl +2 + Co +2 slow Tl +2 + Co +3 Tl +3 + Co +2 fast. If this mechanism is correct, what is the overall reaction? Tl + + 2Co +3 Tl +3 + 2Co +2 what is the rate law? rate = k [Tl + ] [Co +3 ] based on slow step intermediates (if any) Tl +2 catalysts (if any) none 4. The decomposition reaction C 4 H 8 2C 2 H 4 has the Arrhenius parameters A = 4.0 10 15 s-1 and Ea = 261 kJ/mol. What is the value of the rate constant at 800K? 1 800 / / 314 . 8 / 261000 1 15 / 036 . 10 . 4 = = = s e s Ae k K K mol J mol J RT Ea On the calculator, this looks like 4 E 15e^(-261000/8.314/800)...
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