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Department
Chemistry
Course
CHEM 112
Professor
Chris Mc Daniel
Semester
Spring

Description
CHEM-112-01 Spring 2012 Name: ________________________ Class: ___________________ Date: __________ ID: A 1. Record your name and ID number on the scantron form. 2. Record the test ID letter in the top right box of the scantron form. 3. Record all of your answers on the scantron form. DO NOT wait until the end to do this ! 4. Remain seated until the period is over. 5. Pass the scantron form to the center. 6. Take your exam with you. You have 50 minutes. GOOD LUCK ! Exam 1 Multiple Choice Identify the choice that best completes the statement or answers the question. ____ 1. What is the ID letter of your exam? Record this for question 1. a. A d. D b. B e. E c. C ____ 2. Which statement concerning relative rates of reaction is correct for the chemical equation given below? 2 NOBr(g)  2 NO(g) + Br 2(g) a. The rate of appearance of NO is two times the rate of appearance of Br 2. b. The rate of disappearance of NOBr is equal to the rate of appearance of Br 2 c. The rate of appearance of NO is equal to the rate of appearance of Br . 2 d. The rate of disappearance of NOBr is half the rate of appearance of Br 2 e. The rate of disappearance of NOBr is two times the rate of appearance of NO . ____ 3. According to collision theory, which condition(s) must be met in order for molecules to react? 1. The reacting molecules must collide with sufficient energy to initiate the process of breaking and forming bonds. 2. A catalyst must be in contact with the reacting molecules for a reaction to occur. 3. The reacting molecules must collide with an orientation that can lead to rearrangement of the atoms. a. 1 only b. 2 only c. 3 only d. 1 and 2 e. 1 and 3 ____ 4. The reaction A  B follows first-order kinetics with a half-life of 14.3 days. If the concentration of A is 0.024 M after 3.25 days, what is the initial concentration of A? a. 0.028 M b. 0.041 M c. 0.11 M d. 0.021 M e. 0.030 M 1 Name: ________________________ ID: A ____ 5. Molecules must overcome a barrier called the activation energy if they are to react. The highest energy point reached during the progress of a reaction is called the ____. a. rate determining step b. transition state c. intermediate state d. half-life e. elementary step ____ 6. The elementary steps for the catalyzed decomposition of dinitrogen monoxide are shown below. N O(g) + NO(g)  N (g) + NO (g) 2 2 2 2 NO (2)  2 NO(g) + O (g) 2 Which of the following statements is/are CORRECT? 1. The overall balanced reaction is 2 N O2g)  2 N (g) 2 O (g). 2 2. NO(g) is a catalyst for the reaction. 3. NO (g) is a reaction intermediate. 2 a. 1 only b. 2 only c. 3 only d. 1 and 3 e. 1, 2, and 3 ____ 7. If the reaction quotient, Q, is less than K cn a reaction, then a. the reaction will proceed in the forward direction until equilibrium is established. b. the temperature must be increased for the reaction to proceed in the forward direction. c. the reaction will proceed in the backward direction until equilibrium is established. d. the chemical system has reached equilibrium. e. the reaction will proceed in the direction that increases the number of gas phase particles. ____ 8. What is the overall order of the reaction below NO(g) + O (g)  NO (g) + O (g) 3 2 2 if it proceeds via the following rate expression? [N] O È ˘   k[N] O ÎO 3 ˚ t a. zero-order b. fourth-order c. first-order d. third-order e. second-order ____ 9. Nitrosyl bromide decomposes according to the chemical equation below. 2 NOBr(g) 2 NO(g) + Br (2) 1.60 mol of NOBr is dissolved in 1.0 L of solvent and upon establishing equilibrium, 22% of the NOBr decomposed. Calculate the equilibrium constant, K , forcthe reaction? a. 2.8  10 –2 –2 b. 1.40  10 c. 9.93  10 –2 –2 d. 7.96  10 e. 4.5  10 –3 2 Name: ________________________ ID: A ____ 10. 1.10 mol of HCl was dissolved in water to a volume of 2.0 L. It was found that 94.10% of the HCl dissociated to form Cl (aq). What is the equilibrium constant for the reaction? – + HCl(aq) + H O2™) Cl (aq) + H 3 (aq) a. 3.0  10 2 b. 6.0  10 3 c. 0.45 1 d. 1.65  10 e. 0.825  10 1 ____ 11. For a given reaction, the rate constant triples when the temperature is increased from 32 C to 71 C. What is the activation energy for this reaction? (R = 8.314 x 10 kJ/Kmol) a. 53.2 kJ/mol b. 24.6 kJ/mol c. 0.234 kJ/mol d. 3.00 kJ/mol e. 0.532 kJ/mol E / RT ____ 12. The Arrhenius equation, k  Ae a , relates the rate constant of reaction and temperature. A plot of ln(k) versus 1/T will yield a straight line with a slope of ____. a. –E a b. –E aR c. A d. 1/RT Ea/ R e. e ____ 13. A gaseous mixture of NO and N O 2s in eq2il4brium. If the concentration of NO is 1.9  10 mo2/L, what is –3 the concentration of N O2? 2 2 NO 2g) N 2 (4) K c 170 a. 1.9  10 M3 b. 3.8  10 M3 c. 6.1  10 M4 d. 0.85  10 –3 M e. 9.5  10 M4 ____ 14. Which of the following statements is/are CORRECT? 1. For a chemical system, if the reaction quotient (Q) is greater than K, products must be converted to reactants to reach equilibrium. 2. For a chemical system at equilibrium, the forward and reverse rates of reaction are equal. 3. For a chemical system at equilibrium, the concentrations of products divided by the concentrations of reactants equals one. a. 1 only b. 2 only c. 3 only d. 1 and 2 e. 1, 2, and 3 3 Name: ________________________ ID: A ____ 15. The mechanism of a chemical reaction is given below. + – (slow) (CH 3 3CI  (CH ) 3 3 I (CH 3 3C + H O2 [(CH ) CO3 3 2 + (fast) + - [(CH 3 3OH ] 2 I (CH )3 3H + HI (fast) Which of the following statements concerning the reaction is/are CORRECT? 1. The overall balanced reaction is: (CH )3 3 + H O2 (CH ) CO3 3 HI 2. The iodide ion is a reaction intermediate. + + 3. (CH 3 3 , and [(CH )3 3H ] a2e reaction intermediates 4. The following rate law is consistent with the mechanism: rate = k[(CH ) C3 3 a. 1 only b. 2 only c. 3 only d. 1 and 3 e. 1, 3, and 4 __
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