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1 CHM-202 General Chemistry and Laboratory II Unit #2 Take Home Test Due March 14, 2019 Please pass in this completed answer sheet only on the day of the test.

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3 CHM-202 General Chemistry and Laboratory II Unit #2 Take Home Test Due Thursday, March 14, 2019 Directions: Complete this test and pass in the answer sheet portion on or before the due date. Please pass in ONLY the answer sheet. On the answer sheet, be sure to enter your student ID and fill in the appropriate bubbles. Record your answers unambiguously ambiguous answers are wrong. Do not cross out answers either erase/cover them completely or print a new answer sheet. Absolutely no papers will be accepted after the due date. 1. One reaction that contributes to acid rain is the conversion of dinitrogen pentoxide to nitric acid upon reaction with water. How could the rate of this reaction be expressed correctly in terms of the rate at which the concentration of a reactant or product changes? N 2O 5(g) + H 2O(g) 2HNO 3(g) a. Rate = t d. Rate = ½ t b. Rate = t e. Rate = t c. Rate = ½ t 2. If the rate of formation of ammonia is M/s, what is the rate of disappearance of H 2? N 2(g) + 3H 2(g) 2NH 3(g) a M/s d M/s b M/s e M/s c M/s 3. Using the reaction shown below, which statement is correct? H 2(g) + 2ICl(g) I 2(g) + 2HCl(g) a. The concentration of all compounds are changing by the same amount at all times. b. The HCl concentration increases at the same rate as the concentration of iodine. c. The concentration of hydrogen decreases at the same rate as the concentration of ICl. d. The concentration of HCl increases twice as fast as the concentration of iodine. e. None of these statements is correct. 4. In a rate law, the partial orders are determined by a. the reactant concentrations. b. the stoichiometric coefficients. c. the product concentrations. d. experiment. e. the difference between the forward and reverse rates. 5. Consider the rate law expression Rate = k[a][b] 2. Which of the following is not true about the reaction? a. The reaction is second order in B. b. The reaction is first order in A. c. The reaction is overall third order. d. Doubling the concentration of B will double the rate. e. All statements (A D) are true.

4 6. Determine the order of the reaction CH 3CHO(g) CH 4(g) + CO(g) from the following data: Experiment P CH3 CHO Rate mtorr 45.6 mtorr/s mtorr 16.0 mtorr/s a. ½ d. 3 / 2 b. 1 e. 3 c Chlorine dioxide (ClO 2) is used as a disinfectant in municipal water-treatment plants. It decomposes in a first-order reaction with a rate constant of s 1. If the initial concentration were 0.12 M, what would the concentration be after 14.0 s has elapsed? a M d M b M e M c M 8. The energy needed to form an activated complex is called a. collision energy. d. potential energy. b. kinetic energy. e. thermodynamic energy. c. activation energy. 9. The energy profiles for four different reactions are shown below. The scales are the same for each. Which reaction is the most endothermic? a. a c. c b. b d. d

5 10. The high temperatures in an automobile engine cause nitrogen and oxygen to form noxious nitrogen monoxide. Use the following data on the temperature dependence of the rate constant to determine the activation energy for this reaction. T 2200 K 1800 M -1 s K 7400 M -1 s -1 k a. 29 kj/mol d. 310 kj/mol b. 343 kj/mol e. 421 kj/mol c. 78 kj/mol 11. The mechanism for the reaction following reaction, 2H 2O 2(aq) 2H 2O(l) + O 2(g), is proposed to be: Step 1: H 2O 2(aq) + I - (aq) H 2O(l) + OI - (aq) Step 2: H 2O 2(aq) + OI - (aq) H 2O(l) + O 2(g) + I - (aq) Which of the following species is a catalyst? a. I d. OI b. H 2O 2 e. This mechanism has no catalysts. c. H 2O 12. The decomposition of ozone, 2O 3(g) 3O 2(g), is thought to proceed through the following mechanism: Step 1: O 3(g) + NO(g) NO 2(g) + O(g) Step 2: NO 2(g) + O(g) NO(g) + O 2(g) If the rate law = k[o 3][NO], what is the molecularity of steps 1 and 2, and which step is the slow, or rate-determining, step? a. 2; 2; step 1 b. 2; 2; step 2 c. 2; 1; step 1 d. 2; 1; step 2 e. Cannot be determined from the information provided. 13. For the reaction, H 2(g) + I 2(g) 2HI(g), the following mechanism has been suggested: Step 1: (fast) I 2 2I Step 2: (slow) 2I + H 2 2HI a. Rate = k[h 2] b. Rate = k[h 2][I 2] c. Rate = k[h 2] 2 [I 2] d. Rate = k[h 2][I 2] 2 e. Rate = k[i 2] 14. A catalyst that is in a different phase from the reactants and products is a(n) catalyst. a. heterogeneous d. protein b. homogeneous e. exogenous c. enzyme-type

6 15. Which of the following is true for a chemical reaction at equilibrium? a. Only the forward reaction stops. b. Only the reverse reaction stops. c. Both the forward and reverse reactions stop. d. The rate constants for the forward and reverse reactions are equal. e. The rates of the forward and reverse reactions are equal. 16. For an equilibrium reaction with K = , the reverse rate constant was found to be What is the value of the forward rate constant? a d b e c Write the equilibrium expression for the reaction Zn 2+ (aq) + 2NH 3(aq) Zn(NH 3) 2+ (aq) a. K = [Zn 2+ ] + 2[NH 3 ] + [Zn(NH 3 ) 2+ ] d. K = [Zn(NH 3 )2+ ] [Zn 2+ ][NH 3 ] 2 b. K = [Zn2+ ]+2[NH 3 ] Zn(NH 3 ) 2+ e. K = [Zn(NH 3 ) 2+ ] [Zn 2+ ] + 2[NH 3 ] c. K = [Zn2+ ][NH 3 ] 2 Zn(NH 3 ) Water can decompose at an elevated temperature to give hydrogen and oxygen according to the equation below. At a particular temperature, the partial pressures of H 2O, H 2, and O 2 are atm, atm, and atm, respectively, at equilibrium. What is the value of the equilibrium constant, K P, for this reaction at this temperature? 2H 2O(g) 2H 2(g) + O 2(g) a d b e c The equilibrium constant for the formation of hydrogen iodide from hydrogen and iodine is 45.0 at a certain temperature. H 2(g) + I 2(s) 2 HI(g) Which of the following is true regarding this equilibrium? I. The reaction is product-favored. II. The reaction is reactant-favored. III. Equilibrium lies to the right. IV. Equilibrium lies to the left. a. I and III b. I and IV c. II and III d. II and IV e. None are true, as the concentrations of reactants and products are essentially the same.

7 20. The equilibrium constant for the formation of calcium carbonate from the ions in solution is according to the reaction: Ca 2+ (aq) + CO 2-3 (aq) CaCO 3(s) What is the value of the equilibrium constant for the reverse of this reaction? a. the same, d b e c In the following reaction, which of the statements is true, given the pressures of each species? 2SO 2(g) + O 2(g) 2SO 3(g) K p = 0.14 P SO = atm, P O = atm, and P SO = atm a. The reaction is at equilibrium. b. More SO 3 must form to achieve equilibrium. c. More SO 2 and O 2 must form to achieve equilibrium. d. More O 2 must be consumed to achieve equilibrium. e. Equilibrium cannot be established in the system. 22. Which of the following occurs when reactants are added to a chemical reaction in solution or the gas phase at equilibrium? a. Q increases and the equilibrium shifts to produce more products. b. Q increases and the equilibrium shifts to produce more reactants. c. Q decreases and the equilibrium shifts to produce more products. d. Q decreases and the equilibrium shifts to produce more reactants. e. Q is unchanged by the addition of reactants. 23. In the Reaction, Initial, Change, Equilibrium (RICE) table started for calculating equilibrium concentrations of the reaction shown, the terms in the equilibrium row are M 3+ + ML 3 3+ R [M 3+ ] [L] [ML3 3+ ] I 0.15 M 0.40 M 0.0 M C E a x, x, +x. d. 0.15, 0.40, +x. b. x, 3x, +x. e x, x, x. c x, 0.40 x, +x. 24. The reaction of nitrogen gas with oxygen gas, shown here, has a K p value of If a closed vessel was charged with the two reactants, each at an initial partial pressure of atm, what would be the equilibrium partial pressure of NO(g)? N 2(g) + O 2(g) 2NO(g) a atm d atm b atm e atm c atm