4. What volume of 2.0 M NaCl is required to prepare 150 ml of 0.10 M NaCl? a ml b. 1.5 ml c. 7.5 ml d. 75 ml e. 3.0 L

Transcription

1 Chapter 10 Solutions MULTIPLE CHOICE 1. What is the definition of molarity? a. mass of solute per liter of solvent b. mass of solute per kg of solvent c. moles of solute per kg of solvent d. moles of solute in one liter of solvent e. moles of solute per liter of solution 2. To prepare L of M aqueous NaCl (58.4 g/mol), one may a. dissolve g of NaCl in 250 ml of water. b. dissolve 1.46 g of NaCl in 250 ml of water. c. dissolve g of NaCl in enough water to make kg of solution. d. dissolve 1.46 g of NaCl in enough water to make L of solution. e. dissolve g NaCl in kg of water. 3. If ml of 6.00 M HCl is transferred by pipet into a volumetric flask and diluted to 5.00 L, what is the molarity of the diluted HCl? a M b M c M d M e M 4. What volume of 2.0 M NaCl is required to prepare 150 ml of 0.10 M NaCl? a ml b. 1.5 ml c. 7.5 ml d. 75 ml e. 3.0 L 5. To prepare approximately 1 L of m solution of aqueous MgCl 2 (95.2 g/mol), one may a. dissolve 381 g MgCl 2 up to a total volume of 250 ml in a volumetric flask. b. dissolve 381 g MgCl 2 in g of water. c. dissolve 23.8 g MgCl 2 in ml of water. d. dissolve 23.8 g MgCl 2 in kg of water. e. dissolve 23.8 g MgCl 2 in 1.00 kg of water. 6. What mass of Cu(NO 3 ) 2 (187.6 g/mol) is present in 25.0 g of 1.00 m Cu(NO 3 ) 2 (aq)? a g b g c g d g e g 1

2 7. To prepare a solution that is 15.0% aqueous KCl by mass, one should a. dissolve 15.0 g KCl in 85.0 g H 2 O. b. dissolve 15.0 g KCl in g H 2 O. c. dissolve 15.0 g KCl in mol H 2 O. d. dissolve mol KCl in mol H 2 O. e. dissolve mol KCl in 1.00 mol H 2 O. 8. What mass of HCl is required to prepare 1.00 kg of 5.5% by mass aqueous HCl? a g b. 5.5 g c. 18 g d. 55 g e. 550 g 9. What is the mole fraction of NaCl present in a solution that is 12.0% by mass aqueous NaCl? a b c d e The mole fraction of calcium chloride in an aqueous solution is What is the percent mass of CaCl 2 in the solution? a. 4.46% b. 7.24% c. 32.5% d. 36.2% e. 50.0% 11. Concentrated nitric acid is 70.4% HNO 3 by mass. What is the mole fraction of nitric acid? a b c d e Concentrated nitric acid is 70.4% HNO 3 by mass and has a density of 1.42 g/ml. What is the molarity of concentrated nitric acid? a M b M c M d M e M 2

3 13. Concentrated sulfuric acid is 18.0 M and has a density of 1.84 g/ml. Calculate the percent mass of sulfuric acid in concentrated H 2 SO 4. a. 17.7% b. 32.5% c. 78.2% d. 96.0% e. 99.4% 14. Concentrated phosphoric acid is 85.0% by mass H 3 PO 4. If the molarity of concentrated H 3 PO 4 is 14.5 M, what is the density? a g/ml b g/ml c g/ml d g/ml e g/ml 15. Pure acetic acid, often called glacial acetic acid, is a liquid with a density of g/ml. Which calculation correctly shows how to determine the volume of glacial acetic acid necessary to prepare 250 ml of M CH 3 CO 2 H(aq)? Ê molˆê gˆê 1 ml ˆ a L Á L Á mol Á g = Ê b L 1 mol ˆÊ molˆê 1 ml ˆ Á L Á g Á g = Ê molˆê 1 g ˆÊ 1 ml ˆ c L Á L Á mol Á g = Ê molˆê 1 g ˆÊ mlˆ d L Á L Á mol Á 1 g Ê e L 1 mol ˆÊ molˆê 1 ml ˆ Á L Á g Á g = = 16. Pure acetic acid, CH 3 CO 2 H(l), has a density of g/ml. To prepare 1.00 L of 6.00 M CH 3 CO 2 H(aq), one may a. dilute 175 g of acetic acid to a volume of 1.00 L. b. dilute 343 ml of acetic acid to a volume of 1.00 L. c. dilute 360 ml of acetic acid to a volume of 1.00 L. d. dilute 382 ml of acetic acid to a volume of 1.00 L. e. dilute 1049 g of acetic acid to a volume of 1.00 L. 3

4 17. A sample of tap water contains ppm CaCO 3 (aq). Assuming the density of the tap water is 1.00 g/ml, calculate the mass of calcium carbonate in 2.00 L of water. a g b g c g d g e g 18. If sea water contains 15 ppm gold, how many kilograms of sea water must be processed to remove 1.00 g of gold? a. 67 kg b. 97 kg c. 150 kg d kg e kg 19. Silver chloride is a relatively insoluble salt. Only 1.92 mg of AgCl will dissolve per liter of water at 25ºC. How many parts per million of Ag + can be present in water at 25ºC? Assume the density of the solution equals the density of water, 1.00 g/ml. a ppm b ppm c ppm d ppm e ppm 20. Silver chloride is a relatively insoluble salt. Only 1.92 mg of AgCl will dissolve per liter of water at 25ºC. What concentration of Ag +, in molarity units, can be present in water at 25ºC? a M b M c M d M e M 21. A sample of tap water contains 75 ppm aqueous FeCl 3. What is the mass percent of iron(iii) chloride in the tap water? a % b % c % d % e % 4

5 22. A gas mixture has mole fractions of 0.24 oxygen and 0.76 nitrogen. If the total pressure of the gases is 1.44 atm at 325 K, what is the concentration, in molarity, of oxygen? (R = L atm/mol K) a M b M c M d M e M 23. Arrange the molecules below in order of increasing solubility in water. a. dimethyl ether < methane < methanol b. dimethyl ether < methanol < methane c. methane < methanol< dimethyl ether d. methanol < dimethyl ether < methane e. methane < dimethyl ether < methanol 24. All of the following statements are true EXCEPT a. nonpolar substances are usually insoluble in water. b. ionic solids are usually soluble in nonpolar solvents. c. megadoses of water insoluble vitamins, such as A and D, can be toxic. d. water soluble vitamins are readily excreted from one's body. e. alcohols become less soluble as the length of the carbon chain increases. 25. Arrange the molecules below in order of increasing solubility in water. a. methane < methanol < chloromethane b. methane < chloromethane < methanol c. chloromethane < methanol < methane d. chloromethane < methane < methanol e. methanol < methane < chloromethane 5

6 26. All of the following statements are false EXCEPT a. the solubility of a gas in water increases with temperature. b. dissolving a solid in water is usually an endothermic process. c. when an equilibrium is established between molecules in a solid and a solution, the solution is said to be saturated. d. if a precipitate forms when a solution is cooled, the solution is supersaturated. e. network covalent solids are usually soluble in water. 27. All of the following are network covalent solids EXCEPT a. aluminum nitride (AlN). b. silicon dioxide (SiO 2 ). c. graphite (C). d. diamond (C). e. silicon carbide (SiC). 28. A substance that dissolves in water and conducts electricity when present in an aqueous solution is a. metallic. b. ionic. c. molecular. d. network covalent. e. none of the above. 29. Which of the following statements concerning the solubility of a gas in a liquid are true? 1. Solubility decreases with increasing temperature. 2. Solubility decreases as the pressure of the gas over the solution increases. 3. Solubility is independent of the pressure of the gas over the solution. a. 1 only b. 2 only c. 3 only d. 1 and 2 e. 1 and Henry's law states that gas solubility is a. directly proportional to temperature of the solution. b. directly proportional to the molar mass of the gas. c. inversely proportional to the combined pressure of all gases over the solution. d. inversely proportional to the pressure of the gas over the solution. e. directly proportional to the pressure of the gas over the solution. 6

7 31. The Henry's law constant for the solubility of carbon dioxide in water is M/atm at 0.00ºC. If the pressure of CO 2 is atm, what concentration of carbon dioxide can be dissolved in water at 0.00ºC? a M b M c M d M e M 32. The Henry's law constant for the solubility of nitrogen in water is M/atm at 25ºC. At 0.75 atm of N 2, what mass of N 2 (g) dissolves in 1.0 L of water at 25ºC? a g b g c g d g e g 33. In 1.00 atm of pure oxygen, the solubility of O 2 (g) in water is mol/l at 25.0ºC. The mole fraction of oxygen in air is If the atmospheric pressure is 1.00 atm, what is the solubility of oxygen in air at 25.0ºC? a mol/l b mol/l c mol/l d mol/l e mol/l 34. At 1.00 atm, g H 2 (g) will dissolve in 1.0 L of water. What pressure of gas is necessary to obtain a concentration of M H 2 (g)? a atm b atm c. 1.2 atm d atm e atm 35. Which of the following aqueous solutions will have the lowest vapor pressure? a M AlCl 3 b M H 2 SO 4 c M Mg(NO 3 ) 2 d. 1.0 M NaCl e. 1.0 M C 6 H 12 O 6 (glucose) 7

8 36. All of the following are colligative properties EXCEPT a. gas solubility as a function of partial pressure above a solution (Henry's law). b. osmotic pressure. c. vapor pressure lowering. d. boiling point elevation. e. freezing point depression. 37. Which of the following aqueous solutions will freeze at the lowest temperature? a m KCl b m C 6 H 12 O 6 (glucose) c m AlCl 3 d m SrBr 2 e. All of the above freeze at the same temperature. 38. An aqueous solution contains 11.5 g of NaCl in g of water. Calculate the vapor pressure of this solution at 25.0ºC. The vapor pressure of pure water is 23.8 mm Hg at 25.0ºC. a mm Hg b mm Hg c mm Hg d mm Hg e mm Hg mol C 12 H 22 O 11 is added to kg of water and the water is heated to 100ºC. What is the vapor pressure of the solution at this temperature? a mm Hg b. 679 mm Hg c. 712 mm Hg d. 760 mm Hg e. 814 mm Hg 40. What concentration unit is necessary for the calculation of boiling point elevation? a. molarity b. molality c. mass fraction d. mole fraction e. parts per million 41. What concentration unit is necessary for the calculation of vapor pressure lowering? a. molarity b. molality c. mass fraction d. mole fraction e. density 8

9 42. The molal boiling point constant for water is 0.52 ºC/m. At what temperature will a mixture of 45.0 g of NaCl and kg of water boil? a. 98.4ºC b. 99.2ºC c ºC d ºC e ºC 43. The molal freezing point constant for water is 1.86 ºC/m. At what temperature will a mixture of 2.00 g of CaCl 2 and 25.0 g of water freeze? a ºC b ºC c ºC d ºC e ºC 44. Equal masses of water and ethylene glycol (C 2 H 6 O 2 ) are mixed. At what temperature will the mixture freeze? The molal freezing point constant for water is 1.86 ºC/m. a. -115ºC b ºC c ºC d ºC e ºC 45. Pure benzene freezes at 5.50ºC. When g C 10 H 8 (naphthalene, MM = g/mol) is added to g C 6 H 6 (benzene), the mixture freezes at 1.48ºC. What is the freezing point depression constant for benzene? a ºC/m b ºC/m c ºC/m d ºC/m e ºC/m 46. The osmotic pressure of a solution composed of glucose and water is a. directly proportional to the glucose molality. b. directly proportional to the glucose molarity. c. inversely proportional to the glucose molarity. d. inversely proportional to the mass fraction of water. e. inversely proportional to the mole fraction water. 9

10 47. An aqueous solution is composed of 12.8 g glucose (C 6 H 12 O 6, MM = g/mol) diluted to L. Calculate the osmotic pressure of the solution at 35ºC. a atm b atm c atm d. 359 atm e. 727 atm 48. An aqueous solution is composed of 7.50 g NaCl (MM = g/mol) diluted to L. Calculate the osmotic pressure of the solution at 298 K. a atm b atm c atm d atm e atm 49. A solution is prepared by dissolving 5.00 g of an unknown molecular solid in water to make 1.00 L of solution. The osmotic pressure of the solution is 1.61 atm at 25ºC. What is the molar mass of the solute? a g/mol b g/mol c g/mol d. 102 g/mol e g/mol 50. A solution is prepared by dissolving 8.50 g of an unknown nonelectrolyte in kg of water. If the freezing point of the water is depressed by 0.724ºC, what is the molar mass of the solute? The freezing point depression constant for water is 1.86 ºC/m. a g/mol b g/mol c g/mol d g/mol e. 122 g/mol 51. A solution is prepared by dissolving 4.21 g of a nonelectrolyte in 50.0 g of water. If the boiling point increases by 0.203ºC, what is the molar mass of the solute? The boiling point elevation constant for water is ºC/m. a g/mol b. 111 g/mol c. 172 g/mol d. 212 g/mol e. 810 g/mol 10

11 52. Which of the following electrolytes is likely to have a van't Hoff factor equal to 3? a. MgI 2 b. Na 3 PO 4 c. KCl d. answers a and b e. answers a, b, and c 53. A m solution of an unknown electrolyte depresses the freezing point of water by 0.821ºC. What is the Van't Hoff factor for this electrolyte? The freezing point depression constant for water is 1.86 ºC/m. a b c d e