Unit 4 – Review Questions Ch 5 3. What will happen to the height (h) of the mercury column in the manometer shown below if the stopcock is opened, given that the atmospheric pressure is 755 mmHg? 4. 5. 6. A) h will decrease B) h will not change C) h will increase D) not enough information given to answer the question Ans: A Category: Medium Section: 5.2 A pressure that will support a column of Hg to a height of 256 mm would support a column of water to what height? The density of mercury is 13.6 g/cm3; the density of water is 1.00 g/cm3. A) 1.00 × 102 ft B) 18.8 mm C) 33.8 ft D) 76.0 cm E) 348 cm Ans: E Category: Medium Section: 5.2 The pressure of a gas sample was measured to be 654 mmHg. What is the pressure in kPa? (1 atm = 1.01325 × 105 Pa) A) 87.2 kPa D) 8.72 × 104 kPa B) 118 kPa E) 8.72 × 107 kPa C) 6.63 × 104 kPa Ans: A Category: Medium Section: 5.2 The pressure of a gas sample was measured to be 489 mmHg. Which of the following is not an equivalent statement of that pressure? (1 atm = 1.01325 × 105 Pa) A) 65.2 kPa B) 6.52 × 104 Pa C) 489 torr D) 0.811 atm Ans: D Category: Medium Section: 5.2 7. 8. 9. 10. Which of these properties is/are characteristic(s) of gases? A) High compressibility B) Relatively large distances between molecules C) Formation of homogeneous mixtures regardless of the nature of gases D) A and B. E) A, B, and C. Ans: E Category: Easy Section: 5.1 A sample of a gas occupies 1.40 × 103 mL at 25°C and 760 mmHg. What volume will it occupy at the same temperature and 380 mmHg? A) 2,800 mL B) 2,100 mL C) 1,400 mL D) 1,050 mL E) 700 mL Ans: A Category: Medium Section: 5.3 A sample of nitrogen gas has a volume of 32.4 L at 20°C. The gas is heated to 220ºC at constant pressure. What is the final volume of nitrogen? A) 2.94 L B) 19.3 L C) 31.4 L D) 54.5 L E) 356 L Ans: D Category: Medium Section: 5.3 If 30.0 L of oxygen are cooled from 200ºC to 1°C at constant pressure, what is the new volume of oxygen? A) 0.150 L B) 17.4 L C) 23.0 L D) 51.8 L E) 6.00 × 103 L Ans: B Category: Medium Section: 5.3 Ch 11 1. Which one of the following substances is expected to have the highest boiling point? A) Br2 B) Cl2 C) F2 D) I2 Ans: D Category: Easy Section: 11.2 2. Which one of the following substances is expected to have the lowest melting point? A) BrI B) CsI C) LiI D) NaI E) RbI Ans: A Category: Easy Section: 11.2 3. Which one of the following substances is expected to have the highest boiling point? A) HBr B) HCl C) HF D) HI Ans: C Category: Easy Section: 11.2 4. Helium atoms do not combine to form He2 molecules, yet He atoms do attract one another weakly through A) dipole-­‐dipole forces. D) dipole-­‐induced dipole forces. B) ion-­‐dipole forces. E) hydrogen bonding. C) dispersion forces. Ans: C Category: Medium Section: 11.2 5. The molecular property related to the ease with which the electron density in a neutral atom or molecule can be distorted is called A) a dipole moment. D) surface tension. B) polarizability. E) a van der Waals force. C) a dispersion force. Ans: B Category: Easy Section: 11.2 6. Which one of the following substances will have both dispersion forces and dipole-­‐
dipole forces? A) HCl B) BCl3 C) Br2 D) H2 E) CO2 Ans: A Category: Medium Section: 11.2 7. Which one of the following substances should exhibit hydrogen bonding in the liquid state? A) PH3 B) H2 C) H2S D) CH4 E) NH3 Ans: E Category: Medium Section: 11.2 8. Which two properties are more typical of molecular compounds than of ionic compounds? 1. They are gases or liquids at room temperature. 2. They have high melting points. 3. Solids do not conduct electricity, but liquids do. 4. Atoms share electrons. A) 1 and 4 B) 1 and 3 C) 2 and 3 D) 2 and 4 E) 3 and 4 Ans: A Category: Medium Section: 11.2 9. Which of the following substances should have the highest boiling point? A) CH4 B) Cl2 C) Kr D) CH3Cl E) N2 Ans: D Category: Medium Section: 11.2 10. 11. 12. Which of the following substances should have the lowest boiling point? A) CBr4 B) CBr3F C) CBr2F2 D) CBrF3 E) CF4 Ans: E Category: Medium Section: 11.2 13. 18. 19. 20. Which of the following liquids would have the highest viscosity at 25°C? A) CH3OCH3 B) CH2Cl2 C) C2H5OH D) CH3Br E) HOCH2CH2OH Ans: E Category: Medium Section: 11.3 Which of the following liquids would have the lowest viscosity at 25°C? Ans: A Category: Medium Section: 11.3 Which of the following characteristics indicates the presence of weak intermolecular forces in a liquid? A) a low heat of vaporization D) a high boiling point B) a high critical temperature E) None of the above. C) a low vapor pressure Ans: A Category: Easy Section: 11.8 Each of the following substances is a liquid at –50°C. Place these liquids in order of increasing vapor pressure: dimethyl ether (CH3OCH3), propane (C3H8), and ethanol (CH3CH2OH). A) ethanol < propane < dimethyl ether D) dimethyl ether < ethanol < propane B) ethanol < dimethyl ether < propane E) propane < ethanol < dimethyl ether C) propane < dimethyl ether < ethanol Ans: B Category: Medium Section: 11.8 Which of the following would be expected to have the highest vapor pressure at room temperature? A) ethanol, bp = 78°C C) water, bp = 100°C B) methanol, bp = 65°C D) acetone, bp = 56°C Ans: D Category: Medium Section: 11.8 Which of the following would be expected to have the lowest vapor pressure at room temperature? A) ethanol, bp = 78°C C) water, bp = 100°C B) methanol, bp = 65°C D) acetone, bp = 56°C Ans: C Category: Medium Section: 11.8 Ch 12 2. Which one of the following would be immiscible with water? 5. 6. 7. 35. 41. 42. Ans: C Category: Medium Section: 12.2 In which of the following solvents would you expect KBr to be most soluble? A) C6H14 (hexane) D) CCl4 (carbon tetrachloride) B) CH3CH2OH (ethanol) E) C6H12 (cyclohexane) C) C6H6 (benzene) Ans: B Category: Medium Section: 12.2 Which of the following liquids would make a good solvent for iodine, I2? A) HCl B) H2O C) CH3OH D) NH3 E) CS2 Ans: E Category: Medium Section: 12.2 Which of the following compounds should be soluble in CCl4? A) NaCl B) H2O C) NaOH D) C8H18 E) None of these Ans: D Category: Medium Section: 12.2 According to Raoult's law, which statement is false? A) The vapor pressure of a solvent over a solution decreases as its mole fraction increases. B) The solubility of a gas increases as the temperature decreases. C) The vapor pressure of a solvent over a solution is less than that of pure solvent. D) The greater the pressure of a gas over a solution the greater its solubility. E) Ionic solutes dissociate in solution causing an enhancement of all colligative properties. Ans: A Category: Medium Section: 12.6 Dissolving a solute such as KOH in a solvent such as water results in A) an increase in the melting point of the liquid. B) a decrease in the boiling point of the liquid. C) a decrease in the vapor pressure of the liquid. D) no change in the boiling point of the liquid. Ans: C Category: Medium Section: 12.7 What is the freezing point of a solution that contains 10.0 g of glucose (C6H12O6) in 100. g of H2O? Kf for water is 1.86°C/m. A) –0.186°C B) +0.186°C C) –0.10°C D) +0.10°C E) –1.03°C Ans: E Category: Medium Section: 12.6 45. 69. During osmosis A) pure solvent diffuses through a membrane but solutes do not. B) pure solutes diffuse through a membrane but solvent does not. C) pure solvent and a solution both diffuse at the same time through a membrane. D) gases diffuse through a membrane into a solution and build up pressure. Ans: A Category: Medium Section: 12.6 Arrange the following aqueous solutions in order of increasing boiling points: 0.050 m Mg(NO3)2; 0.100 m ethanol; 0.090 m NaCl. A) Mg(NO3)2 < NaCl < ethanol D) NaCl < ethanol < Mg(NO3)2 B) ethanol < Mg(NO3)2 < NaCl E) Mg(NO3)2 < ethanol < NaCl C) ethanol < NaCl < Mg(NO3)2 Ans: B Category: Medium Section: 12.7