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CHEMISTRY A HOMEWORK
UNIT 8 SOLUTIONS
STANDARDS
8. Solutions are homogeneous mixtures of two or more substances. As a basis for
understanding this concept, students will
a) distinguish between solute and solvent.
b) describe the dissolving process at the molecular level by using the concept of
random molecular motion.
c) understand the affects of temperature and pressure on the dissolving process.
d) calculate the concentration of a solute in terms of grams per liter, molarity, parts per
million, mole fraction, and percent composition, and use this information to make
mass, mole, and volume conversions.
e) distinguish between electrolytes and nonelectrolytes.
f) determine, from a solubility curve, if a solution is saturated, unsaturated, or
supersaturated.
g) define saturated, unsaturated, and supersaturated.
h) define colligative properties and give examples.
i) calculate freezing point depression and boiling point elevation
j) explain Raoult’s law.
k) explain Van’t Hoff factor and why it is important.
PROBLEMS
On a separate piece of paper, show all work and express all final answers in the correct
number of significant figures. Box all final answers. Answer all short answer questions
using complete sentences, which infer the question.
1. Why does ammonia have a lower boiling point than water, and a higher boiling point than
methane, CH4?
2. Which of the following would you expect to dissolve in water. Explain why and how?
a) KCl b) NH3 c) CCl4 d) C8H18 e) C2H5OH f) Ca(C2H3O2)2
3. Describe the dissolving process and draw a diagram for the following:
a) 2a
b) 2e
4. Distinguish between a solution, a solvent, and a solute. Give an example of each.
5. Describe how each of the following affect the rate at which a solid solute dissolves in a
solvent.
a) temperature
b) stirring
c) particle size
6. a) Distinguish between a saturated and an unsaturated solution.
b) What is a supersaturated solution and how is it prepared?
c) What can be done to cause a supersaturated solution to crystallize out of solution?
7. What is the effect of pressure and temperature on the solubility of gases in liquids?
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CHEMISTRY A HOMEWORK
UNIT 8 SOLUTIONS
8. Complete the table by giving examples of the following types of solutions.
Type of Solution
Example
Gas-gas
Liquid-gas
Gas-liquid
Liquid-liquid
Solid-liquid
Solid-solid
9. Classify each of the following solutions as electrolytes or nonelectrolytes:
a) HCl b) C6H12O6 c) CaCl2 d) CH3OH e) C4H10
MOLARITY
10. Give the definition of molarity.
11. Calculate the molarity of a solution containing
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a. 1.20 mol of sodium phosphate in 656 cm of solution
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b. 12.0 g of sodium oxalate in 656 cm of solution
c. 15.0 g of potassium hydroxide in 1.24 L of solution
d. 32.0 g of C2H5OH in 94.6 ml of solution
12. Determine the number of moles of solute in
a. 12.0 L of 0.320 M NaCl solution
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b. 159 cm of 0.105 M iron (III) chloride solution
c. 1.69 L of a solution containing 3.45 g of calcium chloride
13. Find the volume of 0.750 M potassium chromate solution that contains
a. 1.00 mol of potassium chromate
b. 0.00600 mol of potassium chromate
c. 1.00 g of potassium chromate
14. You are given 20.0 L of a 0.104 M silver nitrate solution
a. What is the total mass in grams of silver nitrate in this solution?
b. If you want 1.00 mol of silver nitrate what volume of solution should you take?
15. A solution is prepared by dissolving 12.0 g of ethylene glycol, C2H6O2, in water and diluting
to 60.0 ml.
a. What is the molarity of ethylene glycol?
b. What volume of this solution contains 0.100 mol of C2H6O2?
c. How many moles of ethylene glycol are there in 1.00 ml of this solution?
16. Describe in detail how you would prepare each of the following solutions, starting with the
solid.
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a. 500.0 cm of 0.1030 M ammonium chlorite
b. 2.5 L of 0.200 M copper (II) sulfate
c. 750 ml of 1.50 M potassium permanganate
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CHEMISTRY A HOMEWORK
UNIT 8 SOLUTIONS
17. Describe in detail how you would prepare
a. 100.0 ml of 0.100 M HCl from concentrated 12 M HCl.
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b. 2.5 x 10 ml of 1.00 M HCl from 6 M HCl
c. 175 ml of .250 M nitric acid from concentrated 16 M nitric acid.
d. 500.0 ml of 0.050 M iron (III) nitrate from a 2.00 M iron (III) nitrate solution
18. What volume (in ml) of 0.200 M potassium cyanide solution is required to prepare
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3.00 x 10 cm of a potassium cyanide solution with a molarity of 2.50 x 10 ?
PERCENT COMPOSITION (MASS PERCENT)
19. Give the definition of percent composition of a solution.
20. What is the percent composition of a solution prepared by adding 80.0 g of NaOH to 126 g
of water?
21. A solution is prepared by dissolving 18.75 g of calcium acetate in 175.0 g of water.
a) Calculate the percent composition of this solution.
b) Calculate the mass of this solution which contains 5.00 g of calcium acetate.
c) Calculate the mass of calcium acetate in 25.0 0 g of this solution.
22. For a 12.0% (m/m) solution of iron (III) sulfate, calculate
a) the mass of iron (III) sulfate in 25.0 g of solution
b) the mass of water in 75.0 g of solution
c) the mass of solution that contains 6.00 g of iron (III) sulfate
23. A solution is prepared by dissolving 22.75 g of potassium chlorate in 750.0 g of water.
a) Calculate the percent composition of the solution.
b) Calculate the mass of this solution which contains 10.00 g of potassium chlorate.
c) Calculate the mass of potassium chlorate in 500.0 g of this solution.
24. Concentrated sulfuric acid contains 96% (m/m) H2SO4. How many grams of H2SO4 are
there in 58 g of this solution? How many grams of water?
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25. What mass of glucose is needed to prepare 5.00 x 10 g of a solution in which the mass
percent of glucose is 12.0 (m/m)? What mass of water is required?
PARTS PER MILLION
26. Give the definition of parts per million.
27. Calculate the ppm of the solute in each of the following aqueous solutions. (Assume that the
density of the very dilute sample is equal to the density of water, 1.00 g/mL.)
a) 128 mg of sodium ions in 550.0 ml of water
b) 172 mg of potassium ions in 850.0 ml water
c) 2.5 mg of aluminum ions in 1.5 L of ocean water
d) 2.7 x 10-3 mg of gold in 450.0 ml of ocean water
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CHEMISTRY A HOMEWORK
UNIT 8 SOLUTIONS
28. Calculate milligrams of the solute dissolved in the following aqueous solutions. (Assume
that the density of the very dilute sample is equal to the density of water, 1.00 g/mL.)
a) 5.50 L of a water sample having 15 ppm strontium ions.
b) 9.80 L of ocean water having 65 ppm bromide ions.
c) 15.0 L of ocean water having 3.0 x 10-4 ppm silver.
d) 3.0 L of a water sample contining 2.00 x 102 ppm potassium ions
29. Lead is a poisonous metal that especially affects children because they retain a larger
fraction of lead than adults do. Lead levels of 0.250 ppm in a child cause delayed
cognitive development. How many moles of lead present in 1.00 g of a child’s blood
would 0.250 ppm represent?
30. In the United States, drinking water cannot by law contain more than 5.0 x 10-7 g of
mercury per gram of sample. Calculate ppm mercury.
31. A solution is prepared by dissolving 10.00 g of zinc nitrate in 250.0 ml of water.
a) Calculate the mass percent of this solution.
b) Calculate the mass of zinc nitrate in 75.00 g of this solution.
c) Calculate the mass of this solution which contains 3.65 g of zinc nitrate.
d) Calculate the mass of water in 5.00 g of this solution.
32. Write equations for the dissociation of each of the following ionic compounds in solution.
Assuming each is a 0.20 M solution, determine the molarity of ions in each solution.
a) Sodium oxalate
d) Aluminum sulfate
b) Ammonium sulfide
e) Lead (II) acetate
c) Chloric acid
f) Potassium carbonate
33. A solution is prepared by dissolving 20.00 g of iron (III) oxalate in 50.0 ml total solution.
a) Calculate the molarity of this solution.
b) Calculate the volume of this solution which contains 0.500 mols.
c) Calculate the number of moles of iron (III) oxalate in 50.0 ml of this solution.
34. Describe how to prepare the following solutions.
a) 750.0 ml of 1.00 M HNO3 from 6.00 M HNO3.
b) 200.0 ml of 0.500 M sodium phosphate.
35. A solution is prepared by dissolving 25.00 g of sodium carbonate in 750.0 ml. Calculate
the concentration of this solution in grams per liter.
36. Write a balanced equation for the reaction of aluminum with hydrochloric acid.
a) Calculate the mass of aluminum chloride which can be produced from 1.00 g of
aluminum and 10.0 ml of 6.0 M HCl.
b) Calculate the volume of hydrogen gas produce at a temperature of 22 oC and a
pressure of 755.5 mm Hg.
37. Write a balanced equation for the reaction of magnesium with acetic acid.
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CHEMISTRY A HOMEWORK
UNIT 8 SOLUTIONS
a) Calculate the mass of magnesium acetate which can be produced from 0.500 g of
magnesium and 5.00 ml of 3.00 M acetic acid.
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b) Calculate the volume of hydrogen gas produced at a temperature of 24 C and a
pressure of 761.3 mm Hg.
38. Which compound demonstrates the greatest increase in solubility with an increase in
temperature?
a) KCl b) NaCl c) KNO3
d) NH4Cl e) HCl
39. Why do the solubilites of NH3 and SO2 decrease with an increase in temperature?
40. What is the solubility of potassium chlorate at 90 oC in g per liters of water?
41. Describe how to create a supersaturated solution of potassium chloride at 30.0oC.
42. What are colligative properties?
43. State Raoult’s law.
44. What is the molality of a solution prepared by dissolving 7.70 g CH3OH in 125.0 g H2O?
45. What is the molality of the following solutions:
a) 25.0 g of sodium chloride in 500.0 g of water
b) 15.0 g of potassium chloride in 250.0 g of water
c) 0.10 moles of calcium chloride in 500.0 g of water
46. Determine the freezing point and boiling point of the solutions in #45.
UNIT 8 REVIEW
47. A solution is prepared by dissolving 5.00 g of barium nitrate in water to a final volume of
500.0 ml. Calculate
a) the molarity of the solution.
b) the volume of this solution which contains 1.00 x 10-3 moles barium nitrate.
c) moles of barium nitrate in 175.0 ml of this solution.
48. A solution is prepared by dissolving 7.50 g of sodium carbonate in water to a final
volume of 750.0 ml. Calculate
a) the molarity of the solution.
b) the volume of this solution which contains 5.00 x 10-3 moles sodium carbonate.
c) moles of sodium carbonate in 500.0 ml of this solution.
49. A solution is prepared by dissolving 15.0 g of ethylene glycol (C2H6O2) in
25.0 g of water.
a) Calculate the mass percentage concentration of this solution.
b) Calculate the mass of this solution which contains 7.00 g of C2H6O2.
c) Calculate the mass of ethylene glycol in 20.0 g of this solution.
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CHEMISTRY A HOMEWORK
UNIT 8 SOLUTIONS
50. Calculate the percent composition of the following solutions:
a) 25.0 ml of ethanol, C2H5OH, is added to water to a final volume of 125 ml.
b) 15.00 g of sodium oxalate is added to water to a final volume of 750.0 ml.
51. Calculate ppm of the solute in a solution prepared by dissolving 115 mg of mercury (I) ions in
water to a total volume of 1.25 L.
52. Calculate the milligrams of solute dissolved in 10.0 L of an aqueous solution which
contains 75 ppm lead (II) ions.
53. Describe how you would prepare the following solutions:
a) 200 ml of 0.300 M potassium carbonate
b) 100 ml of 0.250 M nitric from 16 M nitric acid
54. a) Calculate the mass of iron (III) chloride which can be produced from 1.00 g of iron
with 10.00 ml of 2.00 M hydrochloric acid.
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b) Calculate the volume of hydrogen gas produced at 22.5 C and 725 mm Hg.
c) Identify the substance which is oxidized? reduced?
55. Identify each of the following substances as an electrolyte or a nonelectrolyte:
a) C2H5OH b) CsCl c) NH4OH d) Cl2O7 e) HC2H3O2
56. Identify each of the following solutions as saturated, supersaturated or unsaturated.
a) A solution is prepared by adding excess salt to water at room temperature, with a
great deal of shaking. The solution is then poured off into a new beaker, leaving the
remaining, undisclosed salt behind.
b) A solution is prepared by adding 10.00 g of salt to water. The solution is left
standing for one hour, and the salt is found to be completely dissolved in the solution
without mixing or heating.
c) A solution is prepared by heating the water and adding as much salt as possible. The
solution is allowed to cool without disturbing. Upon cooling a salt crystal is added
to the solution, and a large amount of salt precipitates out of solution.
57. When a solvent contains as much of the solute as it can hold, the solution is said to be
a) unsaturated
c) supersaturated
b) saturated
d) dilute
58. Which of the following aqueous solutions has the greatest number of ions in solution?
a) 2.0 L of 1.50 M sodium phosphate
b) 3.0 L of 1.50 M sodium chloride
c) 2.0 L of 2.00 M potassium fluoride
d) 1.0 L of 3.00 M sodium sulfate
59. Which of the following actions does not generally increase the rate of a solute dissolving in
a solvent?
a) increasing the surface area of the solute
b) stirring the solution
c) raising the temperature of the solution
d) adding more solute
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CHEMISTRY A HOMEWORK
UNIT 8 SOLUTIONS
60. How do temperature and pressure affect the solubility of a gas?
61. Explain why glucose is soluble in water, while octane, C8H18, is not.
62. Calculate the volume of hydrogen gas at 22.5 oC and 753.8 mm Hg which can be
produced from 2.00 g of magnesium and 5.00 ml of 3.00 M acetic acid. Identify the
substance which is reduced and that which is oxidized.
63. You have equal masses of different solutes dissolved in equal volumes of solution.
Which of the solutes would make the solution with the highest concentration measured
in molarity?
a) NaOH
b) KCl
KOH
d) LiOH
64. Determine the molality of the following
a) 10.0 g of methanol in 1.5 kg of water
b) 1.20 moles of sodium sulfate in 10.0 L of water
c) 2.50 g of calcium nitrate in 25.0 g of water
65. Calculate the freezing point and boiling point of the solutions in question 64.
66. 0.2436-g sample of an unknown substance was dissolved in 20.0 mL of cyclohexane.
The density of cyclohexane is 0.779 g/mL. The freezing-point depression was 2.5ºC.
Calculate the molar mass of the unknown substance (Kf for cyclohexane is 20.2 °C/m).
67. 0.350 g sample of a large biomolecule was dissolved in 15.0 g of chloroform, and the
freezing-point depression was determined to be 0.240°C. Calculate the molar mass of the
biomolecule (Kf for chloroform is 4.70°C·kg/mol).
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