HW12_Solutions

# HW12_Solutions - estrada(gse77 – Homework 12 –...

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Unformatted text preview: estrada (gse77) – Homework 12 – Sutcliffe – (52410) 1 This print-out should have 12 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points The following data were obtained in four sep- arate experiments measuring the initial rates of the reaction A + 2 B + C → products with different concentrations of reactants Initial Initial Initial Initial Trial [A] [B] [C] rate M M M M/s × 10 − 2 × 10 − 2 × 10 − 3 × 10 − 8 1 2 . 3 . 4 . 9 . 70 2 4 . 3 . 4 . 38 . 8 3 4 . 3 . 12 . 116 . 4 4 2 . 6 . 8 . 19 . 4 What are the exponents of [A], [B], and [C] (in that order) in the rate law? 1. 2; 0; 1 correct 2. 2; 1; 1 3. 0; 1; 2 4. 2; 1; 0 5. 0; 1; 1 6. 1; 0; 1 7. 1; 2; 0 8. 1; 1; 1 9. None of these is correct 10. 1; 0; 2 Explanation: The rate law will take the form Rate = k [A] x [B] y [C] z To determine the order of reaction with respect to A, compare trials 1 and 2. rate 2 rate 1 = parenleftbigg initial[A] 2 initial[A] 1 parenrightbigg x 38 . 8 × 10 − 8 M / s 9 . 70 × 10 − 8 M / s = parenleftbigg 4 . × 10 − 2 M 2 . × 10 − 2 M parenrightbigg x 4 = 2 x x = 2 Thus the reaction is second order with re- spect to A. Likewise, to determine the order of reaction with respect to C, compare trials 2 and 3. rate 3 rate 2 = parenleftbigg initial[C] 3 initial[C] 2 parenrightbigg z 116 × 10 − 8 M / s 38 . 8 × 10 − 8 M / s = parenleftbigg 12 . × 10 − 3 M 4 . × 10 − 3 M parenrightbigg z 3 = 3 z z = 1 Thus the reaction is first order with respect to C. Finally, to determine the order of the reac- tion with respect to B, we can compare trials 1 and 4, although both B’s and C’s concen- trations are changing between trials 1 and 4. However, we do know the order of the reaction with respect to C....
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## This note was uploaded on 03/03/2012 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas.

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HW12_Solutions - estrada(gse77 – Homework 12 –...

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