Final - CHEMISTRY 13 FINAL EXAM May 1, 2006 FORM A

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Unformatted text preview: CHEMISTRY 13 FINAL EXAM May 1, 2006 FORM A ---------------------------------------------------------------------------------------------- 1. 14 C is produced continuously in the upper atmosphere as nitrogen atoms capture cosmic-ray neutrons. The 14 C atoms react with oxygen molecules to form 14 CO 2 , and the 14 CO 2 is assimilated by photosynthesis in plants. 14 C has a half-life of 5500 years. If the 14 C in a freshly cut twig gives 16 counts per second of - radiation, how many counts per second will it give after 11000 years? A. 8 counts per sec B. 32 counts per sec C. 3.23 counts per sec D. 2 counts per sec E. 4 counts per sec ------------------------------------------------------------------------------------------------- 2. One of the fusion reactions in the suns interior is shown below. 2 1 H 2 H + X What is X? A. alpha particle B. beta particle C. neutron D. positron E. gamma emission ------------------------------------------------------------------------------------------------ 3. What is the mass defect for the following radioactive decay? 14 N + 1 n 14 C + 1 p The mass of 14 N = 14.003074 amu and 14 C = 14.003241amu A. 1.223 10 3 amu B. 1.008503 amu C. 1.007447 amu D. 1.670 10 4 amu E. 1.390 10 3 amu -------------------------------------------------------------------------------------------------- 4. Consider the following reaction: 2 NO(g) + 2H 2 (g) N 2 (g) + 2H 2 O(g) The rate law for this reaction is first order in H 2 and second order in NO. What would happen to the rate if the initial concentration of NO tripled while all other factors stayed the same? A. The rate will remain constant. B. The rate will double. C. The rate will triple. D. The rate will increase by a factor of 9. E. The rate will decrease by a factor of 3. ------------------------------------------------------------------------------------------------- 5. The mechanism for the gas phase reaction is given below: H 2 + I 2 2 HI I 2 2 I (fast equilibrium) I + H 2 H 2 I (fast equilibrium) H 2 I + I 2 HI (slow) What are the reaction intermediates in the mechanism? A. H 2 I and HI B. I and H 2 C. I and H 2 I D. I and HI E. There are no intermediates. ------------------------------------------------------------------------------------------------- 6. The rate constant of a reaction is tripled when the temperature is increased from 298 K to 308 K. The activation energy, E a , is A. 3.64 kJ mol 1 B. 13.9 kJ mol 1 C. 36.1 kJ mol 1 D. 53.7 kJ mol 1 E. 83.8 kJ mol 1------------------------------------------------------------------------------------------------- 7. The following mechanism has been proposed for the reaction between CO and H 2 to form formaldehyde, H 2 CO: H 2 2 H (fast equilibrium) H + CO HCO (slow) H + HCO H 2 CO (fast) The rate law for this reaction is: A. Rate = k [H 2 ] [CO] B. Rate = k [H 2 ] 1/2 [CO] C. Rate = k [H 2 ] 2 [CO] D. Rate = k [H 2 ] [CO] 2 E. Rate = k [H 2 ] [CO] 1/2-----------------------------------------------------------------------------------------------...
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This note was uploaded on 07/23/2008 for the course CHEM 112 taught by Professor Vandersluys,lorschmid,kylem during the Fall '07 term at Pennsylvania State University, University Park.

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Final - CHEMISTRY 13 FINAL EXAM May 1, 2006 FORM A

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