chem_126_common_1_2009_0s0sANSWER1S_sz0zz

chem_126_common_1_2009_0s0sANSWER1S_sz0zz - Feb. 20, 2009...

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Feb. 20, 2009 Chemistry 126 Common 1 Questions 4-6 1 1.5 2 2.5 3 3.5 0 10 20 30 40 50 60 70 80 Time (min) [R] -1 (M ) [A] has no effect on the rate. From runs 2 and 3, doubling [B] doubles the rate. So the reaction is first order with respect to [B] and the overall reaction order is 0+1 = 1. 1) The overall reaction is 2A(g) + C(s) 2D(g). What is the reaction rate? A. k [A] 2 [C] B. k [A][C] C. k [A] 2 D. k [A] E. Unknown—it must be determined from experimental data 2-3) The table gives the experimental data for the reaction: A(g) + 2B(g) C(g) + D(g) at 500 K. 2) What is the order of the reaction with respect to A? A. 0 B. ½ C. 1 D. 2 E. 3 From runs 1 and 2, changing A has no effect on the rate. 3) What is the overall order of the reaction? (You first need to find the order with respect to B.) A. 0 B. 1 C. 2 D. 3 E. 4 4) 1/reactant concentration is plotted versus time and produces a straight line. What is the order of the reaction? A. 0 B. ½ C. 1 D. 2 E. 3 [ ] [ ] nd 1 1 For 2 order: yields a straight line. o kt R R = + 5) What is the rate constant (include units)? A. 38 M/min B. 38 M -1 min -1 C. 38 M -1 min D. 0.026 M/min E. 0.026 M -1 min -1 6) What is the approximate half-life for a starting concentration of 0.67 M? A. about 5 min B. about 20 min C. about 35 min D. about 60 min E. about 80 m Run [A] (M) [B] (M) Rate (1/hr) 1 0.25 0.15 0.33 2 0.40 0.15 0.33 3 0.80 0.30 0.66 ( 29 1 1 -1 1 3.35 1.25 0.026 min 80min 0min M M k slope M - - - - = = = - [ ] [ ] [ ] [ ] 1 1 1 1/2 -1 1 Starting concentration 0.67 Final concentration 0.5 .67 0.335 1 1 1 1 1.49 ; 3.0 0.67 0.335 Using graph, time to go from 1.5 to 3.0 68 10 58min o M x M M M R R M M - - - - = = = = = = = = - = [ ] [ ] [ ] [ ] ( 29 1 1 1/2 1 1 1 1 : ; 0.026 min 0.335 0.67 1.49/ 0.026 57min o Or solve kt M t R R t - - = + = + = =
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7) Consider the following reaction: 3A(g) + B(g) C(g) + 4D(g). Suppose the concentration of A is 0.51 M and 12.0 s later, it is 0.39 M. What is the average rate of reaction for this time interval? A. 0.0033 M/s B. -0.0033 M/s C. 0.01 M/s D. -0.01 M/s E. 0.12 M/s 8) For the reaction D B + C, the rate constant, k, is 1.0 s -1 at 700. K and k = 2.0 s -1 at 730. K. What is the pre-exponential or Arrhenius factor? A. 17 s k = A e - Ea/RT . So, ln k = ln A E a /RT B. 2.1 x 10 7 s C. 1.1 x 10 4 s D. 1.1 x 10 6 s E. 7.4 x 10 16 s LinReg(ax+b) L2,L4 a = -11,807 = slope = -E a /R b= 16.87 = ln A A = e b = e 16.87 = 2.1 x 10 7 s 9) When dinitrogen pentoxide is heated, it decomposes to nitrogen dioxide and oxygen. It is easy to monitor the total pressure. However, the N 2 O 5 pressure is needed to determine the reaction rate. For the initial
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This note was uploaded on 11/09/2010 for the course CHEM Chem taught by Professor Petrova during the Spring '09 term at NJIT.

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chem_126_common_1_2009_0s0sANSWER1S_sz0zz - Feb. 20, 2009...

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