Exam 4 Practice Problems false false

Transcription

1 Exam 4 Practice Problems 1 1. Which of the following statements is false? a. Condensed states have much higher densities than gases. b. Molecules are very far apart in gases and closer together in liquids and solids. c. Gases completely fill any container they occupy and are easily compressed. d. Vapor refers to a gas formed by evaporation of a liquid or sublimation of a solid. e. Solid water (ice), unlike most substances, is denser than its liquid form (water). 2. Which statement is false? a. The density of a gas is constant as long as its temperature remains constant. b. Gas expands without limit. c. Gases diffuse into each other and mix almost immediately when put into the same container. d. The molecular mass of a gaseous compound is an invariable quantity. e. Pressure must be exerted on a sample of a gas in order to confine it. 3. If the volume of a sample of Ne is tripled while the temperature is held constant, what happens to the pressure of the gas? a. It triples b. It stays the same. c. It doubles. d. It decreases by 1/3. e. It decreases by 1/2. 4. A sample of a gas occupies milliliters at 20.0 C and 600. torr. What volume will it occupy at the same temperature and 800. torr? a ml b ml c ml d ml e ml 5. Ammonia, NH 3, is used to as fertilizer and as a refrigerant. What is the new pressure if 25.0 g of ammonia with a volume of 750 ml at 1.50 atm is expanded to 7.50 L at constant temperature? a. 15 atm b. 114 mm Hg c psi d atm e. 15 mm Hg 6. A sample of oxygen occupies 47.2 liters under a pressure of torr at 25 C. By what percent does the volume of this sample change if the pressure were decreased to 730. torr at 25 C? a. 37.8% b. 41.1% c. 43.4% d. 46.1% e. 69.9% 7. If the volume of a sample of Cl 2 gas is tripled while pressure is held constant, what happens to the absolute temperature? a. It remains constant. b. It decreases by 1/3. c. It triples. d. It increases nine-fold. e. It decreases by 1/6.

2 8. Radon is a radioactive gas found below ground. If a sample of radon occupies 29 ml at 25 C, what volume will it occupy at 500 K? Assume constant pressure. a ml b. 29 ml c. 49 ml d. 17 ml e. 500 ml 9. A sample of nitrogen occupies 5.50 liters under a pressure of 900. torr at 25.0 C. At what temperature will it occupy 10.0 liters at the same pressure? a. 32 C b C c. 154 C d. 269 C e. 370 C 10. A sample of helium occupies 5.00 L at STP. What volume will the sample occupy at 0.0 C and 890. torr? a L b L c L d L e L 11. Which of the following statements about the combined gas law is incorrect? a. At constant temperature the volume occupied by a definite mass of a gas varies inversely with the applied pressure. b. Doubling the volume and pressure of a sample of gas quadruples the absolute temperature. c. At constant pressure the volume occupied by a definite mass of a gas varies inversely with the absolute temperature. d. Halving the volume of a sample of gas while doubling the pressure leaves the absolute temperature unchanged. e. Doubling the volume and pressure of a sample of gas doubles the absolute temperature. 12. A 1 L sample of gas at 25 C and 1 atm pressure is subjected to an increase in pressure and a decrease in temperature. The density of the gas. a. decreases b. increases c. remains the same d. becomes zero e. either increases or decreases, depending on the sizes of the pressure and temperature changes 13. What is the volume occupied by 10.0 grams of NH 3 at STP, if it behaves ideally? a L b L c L d L e L 14. What is the molecular weight of a gas if gram of the gas occupies 48.7 ml at STP? a g/mol b g/mol c g/mol d g/mol e g/mol 2

3 3 15. Given the mass of one mole of gaseous NO is 30.0 grams/mole, calculate the density of NO in grams/liter at STP. a g/l b g/l c g/l d g/l e g/l 16. Calculate the density of O 2, in g/l, at STP. a g/l b g/l c g/l d g/l e g/l 17. What is the volume that 57.0 grams of F 2 would occupy at 227 C and 1.50 atm? a L b L c L d L e. 106 L 18. How many oxygen atoms are contained in a sample of O 2 that occupies ml at 50.0 C and 1.00 atm pressure? a b c d e g sample of a gas occupies a volume of 275 ml at 10. C and 365 torr. What is the molecular weight of the gas? a g/mol b g/mol c g/mol d g/mol e g/mol 20. What is the pressure exerted by a mixture of 14.0 grams of N 2, 71.0 grams of Cl 2, and 16.0 grams of He in a 50.0-liter container at 0 C? a atm b atm c atm d atm e atm 21. A mixture of gas contains g Ar and 1.95 g Xe and has a total pressure of 2.33 atm. What are the partial pressures of each gas? P Ar (atm) P Xe (atm) a b c d e A 10.0-liter vessel contains gas A at a pressure of 300. torr. A 3.0-liter vessel contains gas B at a pressure of 400. torr. Gas A is forced into the second vessel. Calculate the resulting pressure in torr. Assume temperature remains constant.

4 a torr b torr c torr d torr e torr 23. A 75 ml sample of CO 2 is collected over water at 25 C when the atmospheric pressure is 1.05 atm. How many moles of CO 2 are present? The vapor pressure of water at 25 C is 24.3 torr. a b c d e Consider the following gas phase reaction. 4 4HCl(g) + O 2 (g) 2Cl 2 (g) + 2H 2 O(g) What volume of chlorine at STP can be prepared from the reaction of 600. ml of gaseous HCl, measured at STP, with excess O 2, assuming that all the HCl reacts? a ml b. 267 ml c ml d. 425 ml e ml 25. Calculate the weight of KClO 3 that would be required to produce liters of oxygen measured at 127 C and 760. torr. 2KClO 3 (s) 2KCl(s) + 3O 2 (g) a g b g c g d g e g 26. A 10.0 g sample of CaCO 3 is placed in a 10 L container and heated to 500 K. What is the pressure in the container, assuming all the CaCO 3 reacts. CaCO 3 (s) CaO (s) + CO 2 (g) a. 4.1 atm b atm c. 11 atm d. 42 atm e atm

5 27. Silver oxide decomposes completely at temperatures in excess of 300 C to produce metallic silver and oxygen gas. A 1.60-gram sample of impure Ag 2 O gives 72.1 ml of O 2 measured at STP. What is the percentage of Ag 2 O in the original sample? 5 2Ag 2 O(s) 4Ag(s) + O 2 (g) a. 79.6% b. 62.0% c. 86.4% d. 93.3% e. 73.3% 28. If 36.0 g of C 3 H 8 and 112 g of O 2 are placed in a closed container and the mixture is ignited, what is the maximum mass of CO 2 that could be produced? The other product of the reaction is water. a g b g c g d g e. 108 g 29. The average kinetic energy of ideal gas molecules is directly proportional to the. a. volume of the sample b. pressure of the sample c. mass of the molecule d. density of the sample e. absolute temperature of the sample 30. All of the following statements, except one, are important postulates of the kinetic-molecular theory of gases. Which one? a. Gases consist of large numbers of particles in rapid random motion. b. The volume of the molecules of a gas is very small compared to the total volume in which the gas is contained. c. The average kinetic energy of the molecules is inversely proportional to the absolute temperature. d. The time during which a collision between two molecules occurs is negligibly short compared to the time between collisions. e. There are no attractive or repulsive forces between the individual molecules. 31. What is the order of increasing rate of effusion for the following gases? Ar, CO 2, He, N 2 a. N 2 <Ar<CO 2 <He b. Ar<CO 2 <He<N 2 c. Ar<He<CO 2 <N 2 d. CO 2 <N 2 <Ar<He e. CO 2 <Ar<N 2 <He 32. The most significant intermolecular forces of attraction between individual nonpolar atoms or molecules in the gas phase are attractions. a. dispersion b. strong electrostatic c. covalent d. ionic e. strong dipole

6 6 33. The van der Waals constant, a, in the relationship (P + )(V - nb) = nrt is a factor that corrects for a. deviations in the gas constant, R. b. the attractive forces between gas molecules. c. the tendency of the gas molecules to ionize. d. the average velocities of the gas molecules. e. the volume occupied by the gas molecules. 34. The van der Waals constant, b, in the relationship (P + )(V - nb) = nrt is a factor that corrects for a. deviations in the gas constant, R. b. the attractive forces between gas molecules. c. the tendency of the gas molecules to ionize. d. the average velocities of the gas molecules. e. the volume occupied by the gas molecules. 35. Which of the following interactions are the strongest? a. hydrogen bonding force b. ion-ion interactions c. permanent dipole force d. dispersion force e. London force 36. The boiling points of the halogens increase in the order F 2 < Cl 2 < Br 2 < I 2 due to the resulting increasing interactions. a. ion-dipole b. hydrogen-bonding c. ion-ion d. dispersion forces e. permanent dipole-dipole 37. For which of the following would permanent dipole-dipole interactions play an important role in determining physical properties in the liquid state? a. BF 3 b. ClF c. BeCl 2 d. F 2 e. CCl For which of the following would hydrogen bonding not be an important factor in determining physical properties in the liquid state? a. HI b. H 2 O c. HF d. NH 3 e. H 2 O Which response correctly identifies all the interactions that might affect the properties of BrI? a. dispersion force, ion-ion interaction b. hydrogen bonding force, dispersion force c. permanent dipole force d. permanent dipole force, dispersion force e. dispersion force

7 40. Which response includes all of the following compounds that exhibit hydrogen bonding and no other compounds? 7 CH 4, AsH 3, CH 3 NH 2, H 2 Te, HF a. AsH 3, H 2 Te b. CH 3 NH 2, HF c. CH 4, AsH 3, H 2 Te d. AsH 3, CH 3 NH 2 e. HF, H 2 Te 41. Which of the following boils at the highest temperature? a. C 2 H 6 b. C 3 H 8 c. C 4 H 10 d. C 5 H 12 e. C 6 H Which one of the following boils at the lowest temperature? a. H 2 O b. H 2 S c. H 2 Se d. H 2 Te e. H 2 Po

8 Exam 4 Practice Problems Answer Section 8 MULTIPLE CHOICE 1. ANS: E PTS: 1 TOP: Comparison of Solids Liquids and Gases 2. ANS: A PTS: 1 TOP: Composition of the Atmosphere and Some Common Properties of 3. ANS: D PTS: 1 TOP: Boyle's Law 4. ANS: B PTS: 1 TOP: Boyle's Law 5. ANS: B PTS: 1 TOP: Boyle's Law 6. ANS: E PTS: 1 TOP: Boyle's Law 7. ANS: C PTS: 1 TOP: Charles's Law; the Absolute Temperature Scale 8. ANS: C PTS: 1 TOP: Charles's Law; the Absolute Temperature Scale 9. ANS: D PTS: 1 TOP: Charles's Law; the Absolute Temperature Scale 10. ANS: D PTS: 1 TOP: Standard Temperature and Pressure 11. ANS: E PTS: 1 TOP: The Combined Gas Law Equation 12. ANS: B PTS: 1 TOP: Avogadro's Law and the Standard Molar Volume 13. ANS: B PTS: 1 TOP: Avogadro's Law and the Standard Molar Volume 14. ANS: E PTS: 1 TOP: Avogadro's Law and the Standard Molar Volume 15. ANS: D PTS: 1 TOP: Avogadro's Law and the Standard Molar Volume 16. ANS: B PTS: 1 TOP: Avogadro's Law and the Standard Molar Volume 17. ANS: C PTS: 1 TOP: The Ideal Gas Equation 18. ANS: E PTS: 1 TOP: The Ideal Gas Equation 19. ANS: C PTS: 1 TOP: Determinations of Molecular Weights and Molecular Formulas of Gaseous Substances 20. ANS: A PTS: 1 TOP: Dalton's Law of Partial Pressures 21. ANS: B PTS: 1 TOP: Dalton's Law of Partial Pressures 22. ANS: B PTS: 1 TOP: Dalton's Law of Partial Pressures 23. ANS: C PTS: 1 TOP: Dalton's Law of Partial Pressures 24. ANS: C PTS: 1 TOP: Mass-Volume Relationships in Reactions Involving Gases 25. ANS: E PTS: 1 TOP: Mass-Volume Relationships in Reactions Involving Gases 26. ANS: E PTS: 1 TOP: Mass-Volume Relationships in Reactions Involving Gases 27. ANS: D PTS: 1 TOP: Mass-Volume Relationships in Reactions Involving Gases 28. ANS: D PTS: 1 TOP: Mass-Volume Relationships in Reactions Involving Gases 29. ANS: E PTS: 1 TOP: The Kinetic-Molecular Theory 30. ANS: C PTS: 1 TOP: The Kinetic-Molecular Theory 31. ANS: E PTS: 1 TOP: Diffusion and Effusion of Gases 32. ANS: A PTS: 1 TOP: Real Gases: Deviations from Ideality 33. ANS: B PTS: 1 TOP: Real Gases: Deviations from Ideality 34. ANS: E PTS: 1 TOP: Real Gases: Deviations from Ideality 35. ANS: B PTS: 1 TOP: Intermolecular Attractions and Phase Changes 36. ANS: D PTS: 1 TOP: Intermolecular Attractions and Phase Changes 37. ANS: B PTS: 1 TOP: Intermolecular Attractions and Phase Changes 38. ANS: A PTS: 1 TOP: Intermolecular Attractions and Phase Changes 39. ANS: D PTS: 1 TOP: Intermolecular Attractions and Phase Changes 40. ANS: B PTS: 1 TOP: Intermolecular Attractions and Phase Changes 41. ANS: E PTS: 1 TOP: Intermolecular Attractions and Phase Changes 42. ANS: B PTS: 1 TOP: Intermolecular Attractions and Phase Changes