F21 Practice Exam 3 (PDF)

Practice Exam 3 1. How many grams of iron(III) hydroxide (106.87 g/mol) will precipitate if 50.0 mL of 0.500 M sodium hydroxide is added to 75.0 mL of 0.200 M iron(III) nitrate? a. 1.60 g d. 8.02 g b. 0.891 g e. 2.67 g c. 3.56 g 2. W...

Practice Exam 3 1. How many grams of iron(III) hydroxide (106.87 g/mol) will precipitate if 50.0 mL of 0.500 M sodium hydroxide is added to 75.0 mL of 0.200 M iron(III) nitrate? a. 1.60 g d. 8.02 g b. 0.891 g e. 2.67 g c. 3.56 g 2. What volume of a 0.452 M NaOH solution is needed to neutralize 85 mL of a 0.176 M solution of H2SO4? A) 218.3 mL B) 66.2 mL C) 38.4 mL D) 436.6 mL E) 33 mL 3. In the smelting of iron from iron oxide according to the equation , which is oxidized? a. C in CO d. O in Fe2O3 b. C in CO2 e. Fe metal c. Fe in Fe2O3 4. A balloon is filled with 3.00 L of helium at a pressure of 765 torr. What is the volume of the balloon at an altitude where the pressure is 530 torr if the temperature remains constant? a. 0.231 L d. 1.00 L b. 4.33 L e. 3.00 L c. 2.08 L 5.The pressure gauge on a cylinder used to fill balloons with helium shows a pressure of 1275 psi at a temperature of 25.00C. Assuming the cylinder has a volume of 10.0 L, how many grams of helium does the cylinder contain? a. 521 g d. 37.0 g b. 142 g e. 4.00 g c. 6.70  10 −4 g 6. What is the mole fraction of O2 in a gas mixture with a total pressure of 750 torr when the partial pressure of O2 is 125 torr? a. 0.167 d. 0.333 b. 6.00 e. 0.833 c. 0.200 7. Identify the equilibrium expression for the reaction . a. d. b. e. c. 8. For the equilibrium  , the concentrations at equilibrium are [CH4] = 0.3322 M, [H2S] = 0.6644 M, [CS2] = 0.0678 M, and [H2] = 0.2712 M at 1400.0 K. Calculate Kc. a. 0.167 d. 6.00 b. 2.50  10−3 e. 0.694 c. 4.00  102 9. There are many reactions involving nitrogen, oxygen, and nitrogen oxides at high temperatures. At 1000.0 K, the following reactions have the given equilibrium constants:  K1 = 1.5  106  K2 = 1.2  10−5 Calculate the theoretical value of the equilibrium constant for . a. 9.6  10− 17 d. 1.0  10 16 b. 1.6  10 − 11 e. 36 c. 6.7  10 − 7 10.For the equilibrium  , Kp = 0.0017 at 2300 K. At a given point, the partial pressures of the gases are = = 0.660 atm and PNO = 0.0272 atm. Which statement below is true? a. Q  K, so the reaction will continue to make more products. b. Q  K, so the reaction will consume products to make more reactants. c. Q = K, so the system is at equilibrium. d. The value of K will decrease until it is equal to Q. e. The value of K will increase until it is equal to Q. 11. Consider the reaction N2(g) + O2(g) 2NO(g), for which Kc = 0.10 at 2000ºC. Starting with initial concentrations of 0.040 M of N2 and 0.040 M of O2, determine the equilibrium concentration of NO. A) 5.4 × 10–3 M B) 0.0096 M C) 0.011 M D) 0.080 M E) 0.10 M 12.Consider the following equilibrium: . If Kp = 1.61  10−5 at 1400.0 K, calculate Kc. a. 1.40  10−7 d. 0.212 b. 1.85  10−3 e. 1.22  10−9 c. 541 13. For the following reaction at equilibrium, which choice gives a change that will shift the position of equilibrium to favor formation of more products? 2NOBr(g) 2NO(g) + Br2(g); H o = 30 kJ/mol rxn A) increase the total pressure by decreasing the volume B) add more NO C) remove Br2 D) lower the temperature E) remove NOBr selectively  14. Which statement below regarding the equilibrium constant is FALSE? a. When K  1, the concentrations of products are much greater than the concentrations of reactants at equilibrium. b. When K  1, the concentrations of reactants are much greater than the concentrations of products at equilibrium. c. When K = 1, the concentrations of products and reactants at equilibrium are equal. d. When K = 1, the forward and reverse rate constants are equal. e. When K  1, the products and reactants come to equilibrium rapidly. 15. Identify the equilibrium expression for the reaction . a. d. b. e. c. 16. Calculate the volume occupied by 25.2 g of CO2 at 0.84 atm and 25°C (R = 0.08206 L·atm·K-1·mol-1). A) 0.060 L B) 1.34 L C) 16.9 L D) 24.2 L E) 734 L 17. In which of the following compounds is the oxidation number of S equal to +4? a. H2S d. S8 b. S2Cl2 e. Na2SO3 c. MgSO4 18. For the equilibrium  , Kp = 29.1 at 1000.0 K. What is Kc at 1000.0 K for the equilibrium  ? a. 0.0344 d. 0.0172 b. 0.185 e. 0.0687 c. 5.39  4 19. Which of the following is the oxidizing agent in the following reaction? 5Fe2+(aq) + MnO −4 (aq) + 8H+(aq) → 5Fe3+(aq) + Mn2+(aq) + 4H2O(l) A) Fe2+ B) MnO −4 C) H+ D) Mn2+ E) Fe3+ 20. Consider the equilibrium . Which of the following disturbances will NOT cause the system to shift to the right to reestablish equilibrium? a. The partial pressure of CH4 increases. b. The partial pressure of CO decreases. c. The volume decreases. d. The temperature increases. e. All of these will cause the system to shift to the right. 21. A 34.62 mL of 0.1510 M NaOH was needed to neutralize 50.0 mL of an H2SO4 solution. What is the concentration of the original sulfuric acid solution? A) 0.0229 M B) 0.218 M C) 0.0523 M D) 0.209 M E) 0.105 M 22. A standard solution of 0.243 M NaOH was used to determine the concentration of a hydrochloric acid solution. If 46.33 mL of NaOH is needed to neutralize 10.00 mL of the acid, what is the molar concentration of the acid? A) 0.0524 M B) 0.888 M C) 1.13 M D) 2.26 M E) 2.43 M  Answer 1. B 2. B 3. A 4. B 5.B 6.A 7.D 8.B 9.A 10.C 11.C 12.D 13.C 14.E 15.D 16.C 17.E 18.B 19.B 20.C 21. C 22. C