CHAPTER 5 & 6 PRACTICE TEST QUESTIONS

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1 CHAPTER 5 & 6 PRACTICE TEST QUESTIONS Information that most likely will be on the front cover of your exam: R = Latm/molK Rate a f = Rate b w molar mass s b f molar mass a 1 atm = 760 mm Hg = 760 Torr = kpa q = mcδt c H2O = 4.184J/g C J = kg m 2 /s 2 1. A student is performing a calorimetry experiment. Before doing so, she must determine the calorimeter constant for her calorimeter. If she has a coffee cup calorimeter with 20.0 ml of pure water at 25.0 C and adds 50.0 ml of hot water at 75.0 C, the final temperature of the system is 59.3 C. What is the calorimeter constant? a J/ C b J/ C c J/ C d J/ C e J/ C 2. Determine the ΔH rxn (in kj/mol LiOH) if a 100. ml solution of 1.0 M H 2 SO 4 at 25.0 C is mixed with 100. ml of 2.0 M LiOH at 25.0 C in a calorimeter. The final temperature of the solution is 26.5 C, and the calorimeter constant is 10.3 J/ C. Assume the density of the Li 2 SO 4 is 1.05 g/ml and its heat capacity is the same as water. a kj/mol LiOH b kj/mol LiOH c kj/mol LiOH d kj/mol LiOH e kj/mol LiOH

2 3. Under which of the following conditions is SO 2 LEAST likely to behave as an ideal gas? (The boiling point of SO 2 is 10 C at 1 atm) a. 200 C at 1 atm b. 100 C at 1 atm c. 0 C at 1 atm d. 100 C at 2 atm e. 200 C at 2 atm 4. Which of the following reactions corresponds to ΔH f for C 6 H 5 NH 2 (l)? a. C 6 H 5 NH 2 (l) 6C (s) + 1/2 N 2 (g) + 7/2 H 2 (g) b. 6C (s) + 1/2 N 2 (g) + 7/2H 2 (g) C 6 H 5 NH 2 (l) c. C 6 H 5 NH 2 (l) + 21/2 O 2 (g) 6CO 2 (g) + 7H 2 O (g) + NO 2 (g) d. C 12 (s) + 2N (g) + 14H (g) 2 C 6 H 5 NH 2 (l) e. 12C (s) + N 2 (g) + 7H 2 (g) 2 C 6 H 5 NH 2 (l) 5. Determine the volume of a methane filled balloon that contains 2.95 x molecules of methane (CH 4 ) at STP. a L b L c L d L e L 6. Rank the following substances in order of increasing rate of effusion: CO 2, N 2, He, Xe. a. CO 2 < N 2 < He < Xe b. N 2 < CO 2 < He < Xe c. CO 2 < N 2 < Xe < He d. He < N 2 < CO 2 < Xe e. Xe < CO 2 < N 2 < He 7. A 10.0 L sample of N 2 gas contains 1.00 mole of N 2. How many moles of N 2 must be added to the container to obtain a volume of 17.5 L under the same temperature and pressure conditions? a moles b moles c moles d moles e moles

3 8. A gold (C Au = J/g C) metal bar at C is placed in a perfect calorimeter (no heat lost) that is filled with liquid ethanol (C ethanol = 2.46 J/g C) at 20.0 C. If equal masses of gold and ethanol are present, which of the following statements is true? a. The final temperature of the system will be 60.0 C. b. The temperature of the ethanol will increase faster than the temperature of the gold will decrease. c. The final temperature of the system will be closer to the initial temperature of the gold than to the initial temperature of the ethanol. d. It is not possible to draw a conclusion without the actual masses of gold and ethanol. e. None of the above statements are true. 9. A gas mixture containing He, Ne and CO is placed in a 2.1 L container at 30 C and has a total pressure of 2.4 atm. If the mole fractions of He and Ne are 0.29 and 0.40, respectively, how many molecules of CO are present? a x CO molecules b x CO molecules c x CO molecules d x CO molecules e CO molecules 10. Which of the following processes is endothermic? a. H 2 O (l) H 2 O (s) b. CH 4 (g) + O 2 (g) CO 2 (g) + H 2 O (g) c. CH 3 OH (l) CH 3 OH (g) d. 2Na (s) + Cl 2 (g) 2NaCl (s) e. None of the above are endothermic processes. 11. Which of the following processes is exothermic? a. Thermite reaction (class demo): 2Al(s) + Fe 2 O 3 (s) 2Fe(s) + Al 2 O 3 (s) b. Freezing liquid water to make an ice cube. c. The transition of an electron from n=3 to n=1 in a hydrogen atom. d. Zr (s) + O 2 (g) ZrO 2 (s) kj e. All of the above are exothermic processes. 12. Which of the following fuels (carbon compounds in bold), when burned in oxygen as shown below, produce the most heat per mole of CO 2 formed? a. CH 4 (g) + 2 O 2 (g) CO 2 (g) + 2 H 2 O(l) ΔH = 891 kj b. 2 C 2 H 2 (g) + 5 O 2 (g) 4 CO 2 (g) + 2 H 2 O(l) ΔH = 2602 kj c. C 3 H 8 (g) + 5 O 2 (g) 3 CO 2 (g) + 4 H 2 O(l) ΔH = 2217 kj d. C 2 H 4 (g) + 3 O 2 (g) 2 CO 2 (g) + 2 H 2 O(l) ΔH = 1411 kj e. 2 C 2 H 6 (g) + 7 O 2 (g) 4 CO 2 (g) + 6 H 2 O(l) ΔH = 3122 kj

4 13. Determine the effect on volume if pressure is increased by a factor of 4 while the T is decreased from 600 C to 300 C. a. The volume will decrease by a factor of 4. b. The volume will decrease by a factor of 2. c. The volume will increase by a factor of 4 d. The volume will increase by a factor of 2. e. None of the above are correct. 14. Determine the mole fraction (χ) of helium in a gas mixture if the partial pressure of helium is atm. The mixture contains Ar (n=0.51 mole) and N 2 (n=0.22 mole) in addition to the He. The total pressure of the mixture is 1.77 atm. a b c d e What volume of propane (C 3 H 8 ), at 25 C and 1.00 atm, must react to give off 895 kj of heat according to the following thermochemical equation? C 3 H 8 (g) + 5 O 2 (g) 3 CO 2 (g) + 4 H 2 O(l) ΔH = 2217 kj a L b L c L d L e L 16. Which of the following represents ΔH f for K 2 CO 3? a. 2K + (aq) + CO 3 2 (aq) K 2 CO 3 (aq) b. 2K(s) + C(s) + 3/2 O 2 (g) K 2 CO 3 (s) c. 2K + (aq) + C 4+ (aq) + 3O 2 (aq) K 2 CO 3 (aq) d. 4K(s) + 2C(s) + 3O 2 (g) 2K 2 CO 3 (s) e. 2K(s) + C(s) + 3 O(g) K 2 CO 3 (s)

5 17. A 1.0 mole sample of Ar is placed in an empty container and exerts a pressure of 1.00 atm. If 132 g of CO 2 is added to the container, what is the total pressure? a. 4.0 atm b. 2.0 atm c atm d atm e. 8.0 atm 18. When 2.75 g of magnesium reacts with nitrogen to form Mg 3 N 2, the heat evolved is 17.5 kj. Calculate the standard enthalpy of formation of Mg 3 N 2. a kj b kj c. 155 kj d. 464 kj 19. Determine the density of gaseous SF 6 in a L container at STP. a g/l b g/l c g/l d g/l e g/l 20. When 50.0 ml of M H 2 SO 4 is added to 50.0 ml of 1.00 M KOH in a coffee cup calorimeter, the temperature of the solution rises from C to C. Calculate ΔH of this reaction (in kj/mol KOH). Assume that the total volume is the sum of the individual volumes and that the density and specific heat capacity of the solution are the same as that for pure water. a. 112 kj/mol KOH b kj/mol KOH c kj/mol KOH d kj/mol KOH e kj/mol KOH