Ch.9 Solutions
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Problem 1
Classify the following liquid mixtures as heterogeneous or homogeneous. Further classify each homogeneous mixture as a solution or colloid. Hand lotionProblem 2
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 3
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 5
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 11
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 14
The concentration of cholesterol (C₂₇H₄₆O) in blood is approximately 5.0 mM. How many grams of cholesterol are in 250 mL of blood?Problem 17
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 19
The typical concentration of Mg²⁺ in blood is 3 mEq/L. How many milligrams of Mg²⁺ are in 250 mL of blood?Problem 21
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 22
The diagram to the right shows plots of vapor pressure versus temperature for a solvent and a solution.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? 
Problem 22
The diagram to the right shows plots of vapor pressure versus temperature for a solvent and a solution.What is the approximate boiling-point elevation for the solution? Problem 25
What is the osmolarity of the following solutions? a. 0.35 M KBr b. 0.15 M glucose + 0.05 M K₂SO₄Problem 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) 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 27
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 28
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 29
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 33
How can you tell a solution from a colloid?Problem 35
Why does water not dissolve motor oil?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. 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 39
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 43
How is volume/volume percent concentration defined and for what types of solutions is it typically used?Problem 45
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 48
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 solutionProblem 50
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 52
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 58
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 60
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 63
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?
