Download Exam 1 Multiple Choice Questions - General Chemistry Science | CHEM 112 and more Exams Chemistry in PDF only on Docsity!
Exam 1
Multiple Choice Identify the choice that best completes the statement or answers the question. ____ 1. Which of the following statements concerning the attraction of ions to polar molecules is/are CORRECT?
- The energy of attraction between an ion and a polar molecule is directly proportional to the square of the distance between the center of the ion and the oppositely charged pole of the dipole.
- The higher the ion charge, the greater the attraction between the ion and a polar molecule.
- The greater the magnitude of the dipole, the greater the attraction between the ion and a polar molecule. a. 1 only b. 2 only c. 3 only d. 2 and 3 e. 1, 2, and 3 ____ 2. As pure molecular solids, which of the following exhibits dipole-dipole intermolecular forces: HCl, Cl 2 , SCl 2 , and CCl 4? a. HCl only b. HCl and Cl 2 c. HCl and SCl 2 d. Cl 2 and CCl 4 e. SCl 2 and CCl 4 ____ 3. As pure molecular solids, which of the following exhibit only induced dipole/induced dipole forces: O 2 , CH 2 Cl 2 , and SO 2? a. O 2 only b. CH 2 Cl 2 only c. SO 2 only d. O 2 and CH 2 Cl 2 e. O 2 and SO 2 ____ 4. List all the intermolecular forces present in pure acetone. a. hydrogen bonding only b. dipole-dipole force only
c. dipole-dipole force and induced dipole/induced dipole force d. hydrogen bonding and induced dipole/induced dipole force e. hydrogen bonding, dipole-dipole force, and induced dipole/induced dipole force ____ 5. Equilibrium is established between a liquid and its vapor when a. the rate of evaporation equals the rate of condensation. b. equal masses exist in the liquid and gas phases. c. equal concentrations (in molarity) exist in the liquid and gas phases. d. all the liquid has evaporated. e. the liquid ceases to evaporate and the gas ceases to condense. ____ 6. Which of the following liquids has the smallest enthalpy of vaporization? a. C 5 H 12 b. C 4 H 10 c. C 3 H 8 d. C 2 H 6 e. C 6 H 14 ____ 7. At 65.0 °C, water has an equilibrium vapor pressure of 187.5 mm Hg. If 4.78 g H 2 O is sealed in an evacuated 5.00 L flask and heated to 65.0 °C, what mass of H 2 O will be found in the gas phase when liquid-vapor equilibrium is established? Assume any liquid remaining in the flask has a negligible volume. ( R = 0. L⋅atm/mol⋅K, 1 atm = 760 mm Hg) a. 0.0444 g b. 0.801 g c. 1.87 g d. 4.167 g e. 4.78 g ____ 8. Sulfur dioxide has a vapor pressure of 462.7 mm Hg at – 21.0 °C and a vapor pressure of 140.5 mm Hg at – 44.0 °C. What is the enthalpy of vaporization of sulfur dioxide? ( R = 8.314 J/K⋅mol) a. 0.398 kJ/mol b. 6.33 kJ/mol c. 14.0 kJ/mol d. 24.9 kJ/mol e. 39.8 kJ/mol ____ 9. Which of the following phase transitions is/are exothermic?
- liquid water evaporating into the gas phase.
b. +3.8 kJ/mol; increase c. +3.8 kJ/mol; decrease d. +818.4 kJ/mol; increase e. – 818.4 kJ/mol; decrease ____ 14. Which action(s) will increase the equilibrium concentration of a non-reacting gas in water?
- decreasing the temperature of the water
- increasing the volume of water
- decreasing the pressure of the gas above the liquid a. 1 only b. 2 only c. 3 only d. 1 and 3 e. 1, 2, and 3 ____ 15. What is the equilibrium partial pressure of water vapor above a mixture of 44.0 g H 2 O and 56.0 g HOCH 2 CH 2 OH at 35 °C. The partial pressure of pure water at 35.0 °C is 42.2 mm Hg. Assume ideal behavior for the solution. a. 0.730 Hg b. 18.7 mm Hg c. 23.6 mm Hg d. 30.8 mm Hg e. 58.8 mm Hg ____ 16. Which of the following aqueous solutions should have the highest boiling point? a. 0.50 m NaBr b. 0.50 m K 2 SO 4 c. 0.50 m CaBr 2 d. 1.0 m KCl e. 1.5 m C 6 H 12 O 6 ____ 17. What is the freezing point of a solution containing 3.10 grams benzene (molar mass = 78.11 g/mol) dissolved in 32.0 grams paradichlorobenzene? The freezing point of pure paradichlorobenzene is 53.0 °C and the freezing point depression constant, K fp, is – 7.10 °C/ m. a. (^) 44.2 °C b. (^) 51.8 °C c. (^) 52.3 °C d. (^) 54.2 °C e. (^) 61.8 °C
____ 18. What is the boiling point of a solution containing 0.80 g caffeine, C 8 H 10 N 4 O 2 , dissolved in 13.20 g benzene? The boiling point of pure benzene is 80.1 °C and the boiling point elevation constant, K bp, is 2.53 °C/ m. a. (^) 79.8 °C b. (^) 80.4 °C c. (^) 80.9 °C d. (^) 85.2 °C e. (^) 88.2 °C ____ 19. What concentration unit is used in the calculation of osmotic pressure for a dilute solution? a. molality b. weight percent c. mass fraction d. mole fraction e. molarity ____ 20. A solution is prepared by dissolving 4.78 g of an unknown nonelectrolyte in enough water to make 375 mL of solution. The osmotic pressure of the solution is 1.33 atm at 27 °C. What is the molar mass of the solute? ( R = 0.08206 L⋅atm/mol⋅K) a. 0.0203 g/mol b. 21.2 g/mol c. 49.4 g/mol d. 96.8 g/mol e. 236 g/mol
