Ch.9 Solutions
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- Classify the following liquid mixtures as heterogeneous or homogeneous. Further classify each homogeneous mixture as a solution or colloid. Hand lotion
Problem 1
- Which of the following pairs of substances would you expect to form solutions? a. CCl₄ and water b. Benzene (C₆H₆) and MgSO₄ c. Hexane (C₆H₁₄) and heptane (C₇H₁₆) d. Ethyl alcohol (C₂H₅OH) and heptanol (C₇H₁₅OH)
Problem 2
- A solution is prepared by dissolving 12.5 g of KBr in 20 mL of water at 60 °C (see Figure 9.3). Is this solution saturated, unsaturated, or supersaturated? What will happen if the solution is cooled to 10 °C?
Problem 3
- At a total atmospheric pressure of 1.00 atm, the partial pressure of CO₂ in air is approximately 4.0 x 10^-4atm. Using the data in Problem 9.4, what is the solubility of CO₂ in an open bottle of seltzer water at 20 °C?
Problem 5
- The maximum amounts of lead and copper allowed in drinking water are 0.015 mg/kg for lead and 1.3 mg/kg for copper. Express these values in parts per million, and tell the maximum amount of each (in grams) allowed in 100 g of water.
Problem 11
- The concentration of cholesterol (C₂₇H₄₆O) in blood is approximately 5.0 mM. How many grams of cholesterol are in 250 mL of blood?
Problem 14
- The Environmental Protection Agency has set the limit for arsenic in drinking water at 0.010 ppm. To what volume would you need to dilute 1.5 L of water containing 5.0 ppm arsenic to reach the acceptable limit?
Problem 17
- The typical concentration of Mg²⁺ in blood is 3 mEq/L. How many milligrams of Mg²⁺ are in 250 mL of blood?
Problem 19
- When 1.0 mol of HF is dissolved in 1.0 kg of water, the boiling point of the resulting solution is 100.5 °C. Is HF a strong or weak electrolyte? Explain.
Problem 21
- The diagram to the right shows plots of vapor pressure versus temperature for a solvent and a solution.
Problem 22
What is the approximate concentration of the solution in mol/kg, if 1 mol of solute particles raises the boiling point of 1 kg of solvent by 3.63 °C? 
- The diagram to the right shows plots of vapor pressure versus temperature for a solvent and a solution.
Problem 22
What is the approximate boiling-point elevation for the solution? - What is the osmolarity of the following solutions? a. 0.35 M KBr b. 0.15 M glucose + 0.05 M K₂SO₄
Problem 25
- A typical oral rehydration solution (ORS) for infants contains 90 mEq/L Na⁺ , 20 mEq/L K⁺ , 110 mEq/L Cl⁻ and 2.0% (m/v) glucose (MW = 180g/mol) a. Calculate the concentration of each ORS component in units of molarity.
Problem 26
- A typical oral rehydration solution (ORS) for infants contains 90 mEq/L Na⁺ , 20 mEq/L K⁺ , 110 mEq/L Cl⁻ and 2.0% (m/v) glucose (MW = 180g/mol) b. What is the osmolarity of the solution, and how does it compare with the osmolarity of blood plasma?
Problem 26
- Assume that two liquids are separated by a semipermeable membrane, with pure solvent on the right side and a solution of a solute on the left side. Make a drawing that shows the situation after equilibrium is reached.
Problem 27
- When 1 mol of HCl is added to 1 kg of water, the boiling point increases by 1.0 °C, but when 1 mol of acetic acid, CH₃CO₂H is added to 1 kg of water, the boiling point increases by only 0.5 °C. Explain.
Problem 28
- HF is a weak electrolyte and HBr is a strong electrolyte. Which of the curves in the figure represents the change in the boiling point of an aqueous solution when 1 mole of HF is added to 1 kg of water, and which represents the change when 1 mol of HBr is added?
Problem 29
- How can you tell a solution from a colloid?
Problem 33
- Why does water not dissolve motor oil?
Problem 35
- The solubility of NH₃ gas in water at an NH₃ pressure of 760.0 mmHg and 25°C is 51.8 g/100 mL and 27.0 g/100 mL at 50°C. b.How many moles of NH₃ would be released from 1.0 L of a saturated NH₃ solution if the temperature was increased from 25 to 50 °C?
Problem 38
- The solubility of NH₃ gas in water at an NH₃ pressure of 760.0 mmHg and 25°C is 51.8 g/100 mL and 27.0 g/100 mL at 50°C. a.What is the solubility of NH₃ if its partial pressure is reduced to 225.0 mmHg?
Problem 38
- The solubility of CO₂ gas in water is 0.15 g/100 mL at a CO₂ pressure of 760 mmHg. b. An atmospheric concentration of 380 ppm, CO₂ corresponds to a partial pressure of 0.00038 atm. What percentage of the CO₂ originally dissolved in the solution in part (a) remains in solution after the soft drink reaches equilibrium with the ambient atmosphere?
Problem 39
- How is volume/volume percent concentration defined and for what types of solutions is it typically used?
Problem 43
- A dilute aqueous solution of boric acid, H₃BO₃ is often used as an eyewash. How would you prepare 500.0 mL of a 0.50% (m/v) boric acid solution?
Problem 45
- What is the mass/volume percent concentration of the following solutions? a. 0.078 mol KCl in 75 mL of solution b. 0.044 mol sucrose (C₁₂H₂₂ O₁₁) in 380 mL of solution
Problem 48
- How many moles of each substance are needed to prepare the following solutions? a. 50.0 mL of 8.0% (m/v) KCl (MW=74.55g/mol) b. 200.0 mL of 7.5% (m/v) acetic acid (MW=60.05g/mol)
Problem 50
- If you had only 23 g of KOH remaining in a bottle, how many milliliters of 10.0% (m/v) solution could you prepare? How many milliliters of 0.25 M solution?
Problem 52
- Nalorphine, a relative of morphine, is used to combat withdrawal symptoms in heroin users. How many milliliters of a 0.40% (m/v) solution of nalorphine must be injected to obtain a dose of 1.5 mg?
Problem 58
- Sodium thiosulfate (Na₂S₂O₃)the major component in photographic fixer solution, reacts with silver bromide to dissolve it according to the following reaction: AgBr(s)+2 Na₂S₂O₃ (aq) → Na₃Ag(S₂O₃)₂(aq)+ NaBr(aq) b. How many mL of 0.02 M Na₂S₂O₃ contain this number of moles?
Problem 60
- An aqueous solution that contains 285 ppm of potassium nitrate (KNO₃) is being used to feed plants in a garden. What volume of this solution is needed to prepare 2.0 L of a solution that is 75 ppm in KNO₃?
Problem 63
