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10.E: Solutions (Exercises)

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    The following questions are related to the material covered in this chapter. For additional discussion on each topic, also check the links included in each heading.

     

    9.1: Solutions

     

     

    Concept Review Exercises

     

    1. What causes a solution to form?
    2. How does the phrase like dissolves like relate to solutions?

     

    Answers

     

    1. Solutions form because a solute and a solvent have similar intermolecular interactions.
    2. It means that substances with similar intermolecular interactions will dissolve in each other.

     

    Exercises

     

    1. Define solution.

    2. Give several examples of solutions.

    3. What is the difference between a solvent and a solute?

    4. Can a solution have more than one solute in it? Can you give an example?

    5. Does a solution have to be a liquid? Give several examples to support your answer.

    6. Give at least two examples of solutions found in the human body.

    7. Which substances will probably be soluble in water, a very polar solvent?

      1. sodium nitrate (NaNO3)
      2. hexane (C6H14)
      3. isopropyl alcohol [(CH3)2CHOH]
      4. benzene (C6H6)
    8. Which substances will probably be soluble in toluene (C6H5CH3), a nonpolar solvent?

      1. sodium nitrate (NaNO3)
      2. hexane (C6H14)
      3. isopropyl alcohol [(CH3)2CHOH]
      4. benzene (C6H6)
    9. The solubility of alcohols in water varies with the length of carbon chain. For example, ethanol (CH3CH2OH) is soluble in water in any ratio, while only 0.0008 mL of heptanol (CH3CH2CH2CH2CH2CH2CH2OH) will dissolve in 100 mL of water. Propose an explanation for this behavior.

    10. Dimethyl sulfoxide [(CH3)2SO] is a polar liquid. Based on the information in Exercise 9, which do you think will be more soluble in it—ethanol or heptanol?

     

    Answers

     

    1. a homogeneous mixture

    2. vinegar, dextrose IV, saline IV, coffee, tea, wine

    1. A solvent is the majority component of a solution; a solute is the minority component of a solution.

    4. yes. Coke or Pepsi has sugar, caffeine and carbon dioxide as solutes.

    1. A solution does not have to be liquid; air is a gaseous solution, while some alloys are solid solutions (answers will vary).

    6. Urine, plasma

      1. probably soluble
      2. probably not soluble
      3. probably soluble
      4. probably not soluble

    8.

    1. probably not soluble
    2. probably soluble
    3. probably not soluble
    4. probably soluble

    9. Small alcohol molecules have strong polar intermolecular interactions, so they dissolve in water. In large alcohol molecules, the nonpolar end overwhelms the polar end, so they do not dissolve very well in water.

    10. Ethanol is a smaller molecule. It will be more soluble in water than heptanol.

     


    9.2: Concentration

     

     

    Concept Review Exercises

     

    1. What are some of the units used to express concentration?

    2. Distinguish between the terms solubility and concentration.

     

    Answers

     

    1. % m/m, % m/v, ppm, ppb, molarity, and Eq/L (answers will vary)

    2. Solubility is typically a limit to how much solute can dissolve in a given amount of solvent. Concentration is the quantitative amount of solute dissolved at any concentration in a solvent.

     

    Exercises

     

    1. Define solubility. Do all solutes have the same solubility?

    2. Explain why the terms dilute or concentrated are of limited usefulness in describing the concentration of solutions.

    3. If the solubility of sodium chloride (NaCl) is 30.6 g/100 mL of H2O at a given temperature, how many grams of NaCl can be dissolved in 250.0 mL of H2O?

    4. If the solubility of glucose (C6H12O6) is 120.3 g/100 mL of H2O at a given temperature, how many grams of C6H12O6 can be dissolved in 75.0 mL of H2O?

    5. How many grams of sodium bicarbonate (NaHCO3) can a 25.0°C saturated solution have if 150.0 mL of H2O is used as the solvent?

    6. If 75.0 g of potassium bromide (KBr) are dissolved in 125 mL of H2O, is the solution saturated, unsaturated, or supersaturated?

    7. Calculate the mass/mass percent of a saturated solution of NaCl. Use the data from Table 9.E.19.E.1 "Solubilities of Various Solutes in Water at 25°C (Except as Noted)", assume that masses of the solute and the solvent are additive, and use the density of H2O (1.00 g/mL) as a conversion factor.

    8. Calculate the mass/mass percent of a saturated solution of MgCO3 Use the data from Table 9.E.19.E.1 "Solubilities of Various Solutes in Water at 25°C (Except as Noted)", assume that masses of the solute and the solvent are additive, and use the density of H2O (1.00 g/mL) as a conversion factor.

    9. Only 0.203 mL of C6H6 will dissolve in 100.000 mL of H2O. Assuming that the volumes are additive, find the volume/volume percent of a saturated solution of benzene in water.

    10. Only 35 mL of aniline (C6H5NH2) will dissolve in 1,000 mL of H2O. Assuming that the volumes are additive, find the volume/volume percent of a saturated solution of aniline in water.

    11. A solution of ethyl alcohol (C2H5OH) in water has a concentration of 20.56% v/v. What volume of C2H5OH is present in 255 mL of solution?

    12. What mass of KCl is present in 475 mL of a 1.09% m/v aqueous solution?

    13. The average human body contains 5,830 g of blood. What mass of arsenic is present in the body if the amount in blood is 0.55 ppm?

    14. The Occupational Safety and Health Administration has set a limit of 200 ppm as the maximum safe exposure level for carbon monoxide (CO). If an average breath has a mass of 1.286 g, what is the maximum mass of CO that can be inhaled at that maximum safe exposure level?

    15. Which concentration is greater—15 ppm or 1,500 ppb?

    16. Express the concentration 7,580 ppm in parts per billion.

    17. What is the molarity of 0.500 L of a potassium chromate solution containing 0.0650 mol of K2CrO4?

    18. What is the molarity of 4.50 L of a solution containing 0.206 mol of urea [(NH2)2CO]?

    19. What is the molarity of a 2.66 L aqueous solution containing 56.9 g of NaBr?

    20. If 3.08 g of Ca(OH)2 is dissolved in enough water to make 0.875 L of solution, what is the molarity of the Ca(OH)2?

    21. What mass of HCl is present in 825 mL of a 1.25 M solution?

    22. What mass of isopropyl alcohol (C3H8O) is dissolved in 2.050 L of a 4.45 M aqueous C3H8O solution?

    23. What volume of 0.345 M NaCl solution is needed to obtain 10.0 g of NaCl?

    24. How many milliliters of a 0.0015 M cocaine hydrochloride (C17H22ClNO4) solution is needed to obtain 0.010 g of the solute?

    25. Aqueous calcium chloride reacts with aqueous silver nitrate according to the following balanced chemical equation:

      CaCl2(aq) + 2AgNO3(aq) → 2AgCl(s) + Ca(NO3)2(aq)

      How many moles of AgCl(s) are made if 0.557 L of 0.235 M CaCl2 react with excess AgNO3? How many grams of AgCl are made?

    26. Sodium bicarbonate (NaHCO3) is used to react with acid spills. The reaction with sulfuric acid (H2SO4) is as follows:

      2NaHCO3(s) + H2SO4(aq) → Na2SO4(aq) + 2H2O(ℓ) + 2CO2(g)

      If 27.6 mL of a 6.25 M H2SO4 solution were spilled, how many moles of NaHCO3 would be needed to react with the acid? How many grams of NaHCO3 is this?

    27. The fermentation of glucose to make ethanol and carbon dioxide has the following overall chemical equation:

      C6H12O6(aq) → 2C2H5OH(aq) + 2CO2(g)

      If 1.00 L of a 0.567 M solution of C6H12O6 were completely fermented, what would be the resulting concentration of the C2H5OH solution? How many moles of CO2 would be formed? How many grams is this? If each mole of CO2 had a volume of 24.5 L, what volume of CO2 is produced?

    28. Aqueous sodium bisulfite gives off sulfur dioxide gas when heated:

      2NaHSO3(aq) → Na2SO3(aq) + H2O(ℓ) + SO2(g)

      If 567 mL of a 1.005 M NaHSO3 solution were heated until all the NaHSO3 had reacted, what would be the resulting concentration of the Na2SO3 solution? How many moles of SO2 would be formed? How many grams of SO2 would be formed? If each mole of SO2 had a volume of 25.78 L, what volume of SO2 would be produced?

    29. What is the concentration of a 1.0 M solution of K+(aq) ions in equivalents/liter?

    30. What is the concentration of a 1.0 M solution of SO42(aq) ions in equivalents/liter?

    31. A solution having initial concentration of 0.445 M and initial volume of 45.0 mL is diluted to 100.0 mL. What is its final concentration?

    32. A 50.0 mL sample of saltwater that is 3.0% m/v is diluted to 950 mL. What is its final mass/volume percent?

     

    Answers

     

    1. Solubility is the amount of a solute that can dissolve in a given amount of solute, typically 100 mL. The solubility of solutes varies widely.

    2. The term dilute means relatively less solute and the term concentrated implies relatively more solute. Both are of limited usefulness because these are not accurate.

    3. 76.5 g

    4. 90.2 g

    5. 12.6 g

    6. unsaturated

    7. 26.5%

    8. 2.15%

    9. 0.203%

    10. 3.4%

    11. 52.4 mL

    12. 5.18 g

    13. 0.00321 g

    14. 2.57 x 10-4 g

    15. 15 ppm

    16. 7,580,000 ppb

    17. 0.130 M

    18. 0.0458 M

    19. 0.208 M

    20. 0.0475 M

    21. 37.6 g

    22. 548 g

    23. 0.496 L

    24. 20 mL

    25. 0.262 mol; 37.5 g

    26. 0.345 mol; 29.0 g

    27. 1.13 M C2H5OH; 1.13 mol of CO2; 49.7 g of CO2; 27.7 L of CO2

    28. 0.503 M Na2SO3; 0.285 mol SO2; 18.3 g SO2; 471 L SO2

    29. 1.0 Eq/L

    30. 2.0 Eq/L

    31. 0.200 M

    32. 0.16 % m/v

     

    9.3: The Dissolution Process

     

     

    Concept Review Exercise

     

    1. Explain how the solvation process describes the dissolution of a solute in a solvent.

     

    Answer

     

    1. Each particle of the solute is surrounded by particles of the solvent, carrying the solute from its original phase.

     

    Exercises

     

    1. Describe what happens when an ionic solute like Na2SO4 dissolves in a polar solvent.

    2. Describe what happens when a molecular solute like sucrose (C12H22O11) dissolves in a polar solvent.

    3. Classify each substance as an electrolyte or a nonelectrolyte. Each substance dissolves in H2O to some extent.

      1. NH4NO3
      2. CO2
      3. NH2CONH2
      4. HCl
    4. Classify each substance as an electrolyte or a nonelectrolyte. Each substance dissolves in H2O to some extent.

      1. CH3CH2CH2OH
      2. Ca(CH3CO2)2
      3. I2
      4. KOH
    5. Will solutions of each solute conduct electricity when dissolved?

      1. AgNO3
      2. CHCl3
      3. BaCl2
      4. Li2O
    6. Will solutions of each solute conduct electricity when dissolved?

      1. CH3COCH3
      2. N(CH3)3
      3. CH3CO2C2H5
      4. FeCl2

     

    Answers

     

    1. Each ion of the ionic solute is surrounded by particles of solvent, carrying the ion from its associated crystal.

    2. Each sucrose molecule is surrounded by solvent molecules (attracted to each other via intermolecular forces of attraction).

      1. electrolyte
      2. nonelectrolyte
      3. nonelectrolyte
      4. electrolyte

    4.

    • nonelectrolyte
    • electrolyte
    • nonelectrolyte
    • electrolyte

    5.

    1. yes
    2. no
    3. yes
    4. yes

    6.

    a. no

    b. no

    c. no

    d. yes

     


    9.4: Properties of Solutions

     

     

    Concept Review Exercises

     

    1. What are the colligative properties of solutions?

    2. Explain how the following properties of solutions differ from those of the pure solvent: vapor pressure, boiling point, freezing point, and osmotic pressure.

     

    Answers

     

    1. Colligative properties are characteristics that a solution has that depend on the number, not the identity, of solute particles.

    2. In solutions, the vapor pressure is lower, the boiling point is higher, the freezing point is lower, and the osmotic pressure is higher.

     

    Exercises

     

    1. In each pair of aqueous systems, which will have the lower vapor pressure?

      1. pure water or 1.0 M NaCl
      2. 1.0 M NaCl or 1.0 M C6H12O6
      3. 1.0 M CaCl2CaCl2 or 1.0 M (NH4)3PO4
    2. In each pair of aqueous systems, which will have the lower vapor pressure?

      1. 0.50 M Ca(NO3)2 or 1.0 M KBr
      2. 1.5 M C12H22O11 or 0.75 M Ca(OH)2
      3. 0.10 M Cu(NO3)2 or pure water
    3. In each pair of aqueous systems, which will have the higher boiling point?

      1. pure water or a 1.0 M NaCl
      2. 1.0 M NaCl or 1.0 M C6H12O6
      3. 1.0 M CaCl2CaCl2 or 1.0 M (NH4)3PO4
    4. In each pair of aqueous systems, which will have the higher boiling point?

      1. 0.50 M Ca(NO3)2 or 1.0 M KBr
      2. 1.5 M C12H22O11 or 0.75 M Ca(OH)2
      3. 0.10 M Cu(NO3)2 or pure water
    5. Estimate the boiling point of each aqueous solution. The boiling point of pure water is 100.0°C.

      1. 0.50 M NaCl
      2. 1.5 M Na2SO4
      3. 2.0 M C6H12O6
    6. Estimate the freezing point of each aqueous solution. The freezing point of pure water is 0.0°C.

      1. 0.50 M NaCl
      2. 1.5 M Na2SO4
      3. 2.0 M C6H12O6
    7. Explain why salt (NaCl) is spread on roads and sidewalks to inhibit ice formation in cold weather.

    8. Salt (NaCl) and calcium chloride (CaCl2) are used widely in some areas to minimize the formation of ice on sidewalks and roads. One of these ionic compounds is better, mole for mole, at inhibiting ice formation. Which is that likely to be? Why?

    9. What is the osmolarity of each aqueous solution?

      1. 0.500 M NH2CONH2
      2. 0.500 M NaBr
      3. 0.500 M Ca(NO3)2
    10. What is the osmolarity of each aqueous solution?

      1. 0.150 M KCl
      2. 0.450 M (CH3)2CHOH
      3. 0.500 M Ca3(PO4)2

    11. A 1.0 M solution of an unknown soluble salt has an osmolarity of 3.0 osmol. What can you conclude about the salt?

    12. A 1.5 M NaCl solution and a 0.75 M Al(NO3)3 solution exist on opposite sides of a semipermeable membrane. Determine the osmolarity of each solution and the direction of solvent flow, if any, across the membrane.

     

    Answers

     

      1. 1.0 M NaCl
      2. 1.0 M NaCl
      3. 1.0 M (NH4)3PO4

    2.

    • 1.0 M KBr
    • 0.75 M Ca(OH)2
    • 0.10 M Cu(NO3)2

    3.

    1. 1.0 M NaCl
    2. 1.0 M NaCl
    3. 1.0 M (NH4)3PO4

    4.

    • 1.0 M KBr
    • 0.75 M Ca(OH)2
    • 0.10 M Cu(NO3)2

    5.

    1. 100.5°C
    2. 102.3°C
    3. 101°C

    6.

    1. -1.9°C
    2. -8.6°C
    3. -3.8°C

    7. NaCl lowers the freezing point of water, so it needs to be colder for the water to freeze.

    8. CaCl2 splits up into 3 ions while NaCl splits up into 2 ions only. CaCl2 will be more effective.

    9.

    1. 0.500 osmol
    2. 1.000 osmol
    3. 1.500 osmol

    10.

    1. 0.300 osmol
    2. 0.450 osmol
    3. 2.50 osmol

    11. It must separate into three ions when it dissolves.

    12. Both NaCl and Al(NO3)have 3.0 osmol. There will be no net difference in the solvent flow.

    11.4: Dilutions and Concentrations

    1. What is the difference between dilution and concentration?
    2. What quantity remains constant when you dilute a solution?
    3. A 1.88 M solution of NaCl has an initial volume of 34.5 mL. What is the final concentration of the solution if it is diluted to 134 mL?
    4. A 0.664 M solution of NaCl has an initial volume of 2.55 L. What is the final concentration of the solution if it is diluted to 3.88 L?
    5. If 1.00 mL of a 2.25 M H2SO4 solution needs to be diluted to 1.00 M, what will be its final volume?
    6. If 12.00 L of a 6.00 M HNO3 solution needs to be diluted to 0.750 M, what will be its final volume?
    7. If 665 mL of a 0.875 M KBr solution are boiled gently to concentrate the solute to 1.45 M, what will be its final volume?
    8. If 1.00 L of an LiOH solution is boiled down to 164 mL and its initial concentration is 0.00555 M, what is its final concentration?
    9. How much water must be added to 75.0 mL of 0.332 M FeCl3(aq) to reduce its concentration to 0.250 M?
    1. How much water must be added to 1.55 L of 1.65 M Sc(NO3)3(aq) to reduce its concentration to 1.00 M?

    Answers

    1. Dilution is a decrease in a solution’s concentration, whereas concentration is an increase in a solution’s concentration.
    2.  
    3. 0.484 M
    4.  
    5. 2.25 mL
    6.  
    7. 401 mL
    8.  
    9. 24.6 mL

    11.5: Concentrations as Conversion Factors

    1. Using concentration as a conversion factor, how many moles of solute are in 3.44 L of 0.753 M CaCl2?
    2. Using concentration as a conversion factor, how many moles of solute are in 844 mL of 2.09 M MgSO4?
    3. Using concentration as a conversion factor, how many liters are needed to provide 0.822 mol of NaBr from a 0.665 M solution?
    4. Using concentration as a conversion factor, how many liters are needed to provide 2.500 mol of (NH2)2CO from a 1.087 M solution?
    5. What is the mass of solute in 24.5 mL of 0.755 M CoCl2?
    6. What is the mass of solute in 3.81 L of 0.0232 M Zn(NO3)2?
    7. What volume of solution is needed to provide 9.04 g of NiF2 from a 0.332 M solution?
    8. What volume of solution is needed to provide 0.229 g of CH2O from a 0.00560 M solution?
    9. What volume of 3.44 M HCl will react with 5.33 mol of CaCO3? 2HCl + CaCO3 → CaCl2 + H2O + CO2
    10. What volume of 0.779 M NaCl will react with 40.8 mol of Pb(NO3)2? Pb(NO3)2 + 2NaCl → PbCl2 + 2NaNO3
    11. What volume of 0.905 M H2SO4 will react with 26.7 mL of 0.554 M NaOH? H2SO4 + 2NaOH → Na2SO4 + 2H2O
    12. What volume of 1.000 M Na2CO3 will react with 342 mL of 0.733 M H3PO4? 3Na2CO3 + 2H3PO4 → 2Na3PO4 + 3H2O + 3CO2
    13. It takes 23.77 mL of 0.1505 M HCl to titrate with 15.00 mL of Ca(OH)2. What is the concentration of Ca(OH)2? You will need to write the balanced chemical equation first.
    14. It takes 97.62 mL of 0.0546 M NaOH to titrate a 25.00 mL sample of H2SO4. What is the concentration of H2SO4? You will need to write the balanced chemical equation first.
    15. It takes 4.667 mL of 0.0997 M HNO3 to dissolve some solid Cu. What mass of Cu can be dissolved? Cu + 4HNO3(aq) → Cu(NO3)2(aq) + 2NO2 + 2H2O
    16. It takes 49.08 mL of 0.877 M NH3 to dissolve some solid AgCl. What mass of AgCl can be dissolved? AgCl(s) + 4NH3(aq) → Ag(NH3)4Cl(aq)
    17. What mass of 3.00% H2O2 is needed to produce 66.3 g of O2(g)? 2H2O2(aq) → 2H2O(ℓ) + O2(g)
    1. A 0.75% solution of Na2CO3 is used to precipitate Ca2+ ions from solution. What mass of solution is needed to precipitate 40.7 L of solution with a concentration of 0.0225 M Ca2+(aq)?

    Na2CO3(aq) + Ca2+(aq) → CaCO3(s) + 2Na+(aq)

    Answers

    1. 2.59 mol
    2.  
    3. 1.24 L
    4.  
    5. 2.40 g
    6.  
    7. 0.282 L
    8.  
    9. 3.10 L
    10.  
    11. 8.17 mL
    12.  
    13. 0.1192 M
    14.  
    15. 7.39 mg
    16.  
    17. 4.70 kg

    11.6: Colligative Properties of Solutions

    1. What are the three colligative properties that involve phase changes?
    2. Which colligative property does not involve a phase change? Give an example of its importance.
    3. If 45.0 g of C6H6 and 60.0 g of C6H5CH3 are mixed together, what is the mole fraction of each component?
    4. If 125 g of N2 are mixed with 175 g of O2, what is the mole fraction of each component?
    5. If 36.5 g of NaCl are mixed with 63.5 g of H2O, what is the mole fraction of each component?
    6. An alloy of stainless steel is prepared from 75.4 g of Fe, 12.6 g of Cr, and 10.8 g of C. What is the mole fraction of each component?
    7. A solution is made by mixing 12.0 g of C10H8 in 45.0 g of C6H6. If the vapor pressure of pure C6H6 is 76.5 torr at a particular temperature, what is the vapor pressure of the solution at the same temperature?
    8. A solution is made by mixing 43.9 g of C6H12C6 in 100.0 g of H2O. If the vapor pressure of pure water is 26.5 torr at a particular temperature, what is the vapor pressure of the solution at the same temperature?
    9. At 300°C, the vapor pressure of Hg is 32.97 torr. If 0.775 g of Au were dissolved into 3.77 g of Hg, what would be the vapor pressure of the solution?
    10. At 300°C, the vapor pressure of Hg is 32.97 torr. What mass of Au would have to be dissolved in 5.00 g of Hg to lower its vapor pressure to 25.00 torr?
    11. If 25.0 g of C6H12O6 are dissolved in 100.0 g of H2O, what is the boiling point of this solution?
    12. If 123 g of C10H16O are dissolved in 355 g of C6H6, what is the boiling point of this solution?
    13. If 1 mol of solid CBr4 is mixed with 2 mol of CCl4, what is the boiling point of this solution?
    14. A solution of C2H2O4 in CH3COOH has a boiling point of 123.40°C. What is the molality of the solution?
    15. If 123 g of C10H16O are dissolved in 355 g of C6H6, what is the freezing point of this solution?
    16. If 25.0 g of C6H12O6 are dissolved in 100.0 g of H2O, what is the freezing point of this solution?
    17. C8H17OH is a nonvolatile solid that dissolves in C6H12. If 7.22 g of C8H17OH is dissolved in 45.3 g of C6H12, what is the freezing point of this solution?
    18. A solution of C2H2O4 in CH3COOH has a freezing point of 10.00°C. What is the molality of the solution?
    19. If 25.0 g of C6H12O6 are dissolved in H2O to make 0.100 L of solution, what is the osmotic pressure of this solution at 25°C?
    20. If 2.33 g of C27H46O are dissolved in liquid CS2 to make 50.00 mL of solution, what is the osmotic pressure of this solution at 298 K?
    21. At 298 K, what concentration of solution is needed to have an osmotic pressure of 1.00 atm?
    1. The osmotic pressure of blood is about 7.65 atm at 37°C. What is the approximate concentration of dissolved solutes in blood? (There are many different solutes in blood, so the answer is indeed an approximation.)

    Answers

    1. boiling point elevation, freezing point depression, vapor pressure depression
    2.  
    3. mole fraction C6H6: 0.469; mole fraction C6H5CH3: 0.531
    4.  
    5. mole fraction NaCl: 0.157; mole fraction H2O: 0.843
    6.  
    7. 65.8 torr
    8.  
    9. 27.26 torr
    10.  
    11. 100.71°C
    12.  
    13. 92.9°C
    14.  
    15. −5.65°C
    16.  
    17. −18.3°C
    18.  
    19. 33.9 atm
    20.  
    21. 0.0409 M
    Additional Exercises
    1. One brand of ethyl alcohol (Everclear) is 95% ethyl alcohol, with the remaining 5% being water. What is the solvent and what is the solute of this solution?
    2. Give an example of each type of solution from your own experience.
      1. A solution composed of a gas solute in a liquid solvent.
      2. A solution composed of a solid solute in a liquid solvent.
      3. A solution composed of a liquid solute in a liquid solvent.
      4. A solution composed of a solid solute in a solid solvent. (Hint: usually such solutions are made as liquids and then solidified.)
    3. Differentiate between the terms saturated and concentrated.

    4. Differentiate between the terms unsaturated and dilute.

    5. What mass of FeCl2 is present in 445 mL of 0.0812 M FeCl2 solution?

    6. What mass of SO2 is present in 26.8 L of 1.22 M SO2 solution?

    7. What volume of 0.225 M Ca(OH)2 solution is needed to deliver 100.0 g of Ca(OH)2?

    8. What volume of 12.0 M HCl solution is needed to obtain exactly 1.000 kg of HCl?

    9. The World Health Organization recommends that the maximum fluoride ion concentration in drinking water is 1.0 ppm. Assuming water has the maximum concentration, if an average person drinks 1,920 mL of water per day, how many milligrams of fluoride ion are being ingested?

    10. For sanitary reasons, water in pools should be chlorinated to a maximum level of 3.0 ppm. In a typical 5,000 gal pool that contains 21,200 kg of water, what mass of chlorine must be added to obtain this concentration?

    11. Given its notoriety, you might think that uranium is very rare, but it is present at about 2–4 ppm of the earth's crust, which is more abundant than silver or mercury. If the earth's crust is estimated to have a mass of 8.50 × 1020 kg, what range of mass is thought to be uranium in the crust?

    12. Chromium is thought to be an ultratrace element, with about 8.9 ng present in a human body. If the average body mass is 75.0 kg, what is the concentration of chromium in the body in pptr?

    13. What mass of 3.00% H2O2 solution is needed to produce 35.7 g of O2(g) at 295 K at 1.05 atm pressure?

      2H2O2(aq) → 2H2O(ℓ) + O2(g)
    14. What volume of pool water is needed to generate 1.000 L of Cl2(g) at standard temperature and pressure if the pool contains 4.0 ppm HOCl and the water is slightly acidic? The chemical reaction is as follows:

      HOCl(aq) + HCl(aq) → H2O(ℓ) + Cl2(g)

      Assume the pool water has a density of 1.00 g/mL.

    15. A 0.500 m solution of MgCl2 has a freezing point of −2.60°C. What is the true van 't Hoff factor of this ionic compound? Why is it less than the ideal value?

    16. The osmotic pressure of a 0.050 M LiCl solution at 25.0°C is 2.26 atm. What is the true van 't Hoff factor of this ionic compound? Why is it less than the ideal value?

    17. Order these solutions in order of increasing boiling point, assuming an ideal van 't Hoff factor for each: 0.10 m C6H12O6, 0.06 m NaCl, 0.4 m Au(NO3)3, and 0.4 m Al2(SO4)3.

    18. Order these solutions in order of decreasing osmotic pressure, assuming an ideal van 't Hoff factor: 0.1 M HCl, 0.1 M CaCl2, 0.05 M MgBr2, and 0.07 M Ga(C2H3O2)3

    Answers
    1. solvent: ethyl alcohol; solute: water
    2.  
    3. Saturated means all the possible solute that can dissolve is dissolved, whereas concentrated implies that a lot of solute is dissolved.

    4.  
    5. 4.58 g

    6.  
    7. 6.00 L

    8.  
    9. 1.92 mg

    10.  
    11. 1.7 × 1015 to 3.4 × 1015 kg

    12.  
    13. 2,530 g

    14.  
    15. 2.80; it is less than 3 because not all ions behave as independent particles.

    16.  
    17. 0.10 m C6H12O6 < 0.06 m NaCl < 0.4 m Au(NO3)3 < 0.4 m Al2(SO4)3


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