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Problem 62
A dioxin-contaminated water source contains 0.085% dioxin by mass. How much dioxin is present in 2.5 L of this water? Assume a density of 1.00 g/mL.
- A hard water sample contains 0.0085% Ca by mass (in the form of Ca2+ ions). How much water (in grams) contains 1.2 g of Ca? (1.2 g of Ca is the recommended daily allowance of calcium for adults between 19 and 24 years old.)
Problem 63
Problem 64
Lead is a toxic metal that affects the central nervous system. A Pb-contaminated water sample contains 0.0011% Pb by mass. How much of the water (in mL) contains 150 mg of Pb? (Assume a density of 1.0 g/mL.)
- You can purchase nitric acid in a concentrated form that is 70.3% HNO3 by mass and has a density of 1.41 g>mL. Describe exactly how you would prepare 1.15 L of 0.100 M HNO3 from the concentrated solution.
Problem 65
Problem 67
Describe how to prepare each solution from the dry solute and the solvent. a. 1.00×102 mL of 0.500 M KCl b. 1.00×102 g of 0.500 m KCl c. 1.00×102 g of 5.0% KCl solution by mass
Problem 68b
Describe how to prepare each solution from the dry solute and the solvent. b. 125 g of 0.100 m NaNO3
Problem 68c
Describe how to prepare each solution from the dry solute and the solvent. c. 125 g of 1.0% NaNO3 solution by mass
- For a solution prepared by dissolving 28.4 g of glucose (C6H12O6) in 355 g of water with a final volume of 378 mL, calculate the concentration in each unit: a. molarity, b. molality, c. percent by mass, d. mole fraction, e. mole percent.
Problem 69
Problem 70a
A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in 100.0 mL of water at 25 °C. The final volume of the solution is 118 mL. The densities of methanol and water at this temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this solution, calculate the concentration in each unit. a. molarity
Problem 70b
A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in 100.0 mL of water at 25 °C. The final volume of the solution is 118 mL. The densities of methanol and water at this temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this solution, calculate the concentration in each unit. b. molality
Problem 70c
A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in 100.0 mL of water at 25 °C. The final volume of the solution is 118 mL. The densities of methanol and water at this temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this solution, calculate the concentration in each unit. c. percent by mass
Problem 70e
A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in 100.0 mL of water at 25 °C. The final volume of the solution is 118 mL. The densities of methanol and water at this temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this solution, calculate the concentration in each unit. e. mole percent
Problem 71
Household hydrogen peroxide is an aqueous solution containing 3.0% hydrogen peroxide by mass. What is the molarity of this solution? (Assume a density of 1.01 g/mL.)
Problem 72
One brand of laundry bleach is an aqueous solution containing 4.55% sodium hypochlorite (NaOCl) by mass. What is the molarity of this solution? (Assume a density of 1.02 g/mL.)
Problem 73
An aqueous solution contains 25% HCl by mass. Calculate the molality and mole fraction of the solution.
- Which beaker shows a greater decrease in liquid level after being left side by side on a lab bench for 1 week, a beaker with 100.0 mL of pure water or a beaker with 100.0 mL of seawater, and why?
Problem 75
Problem 76
Which solution has the highest vapor pressure? a. 20.0 g of glucose (C6H12O6) in 100.0 mL of water b. 20.0 g of sucrose (C12H22O11) in 100.0 mL of water c. 10.0 g of potassium acetate KC2H3O2 in 100.0 mL of water
Problem 77
Calculate the vapor pressure of a solution containing 38.3 g of glycerin (C3H8O3) in 135 mL of water at 30.0 °C. The vapor pressure of pure water at this temperature is 31.8 torr. Assume that glycerin is not volatile and dissolves molecularly (i.e., it is not ionic), and use a density of 1.00 g>mL for the water.
Problem 79d
A solution contains 50.0 g of heptane (C7H16) and 50.0 g of octane (C8H18) at 25 °C. The vapor pressures of pure heptane and pure octane at 25 °C are 45.8 torr and 10.9 torr, respectively. Assuming ideal behavior, answer the following: d. Why is the composition of the vapor different from the composition of the solution?
Problem 80
A solution contains a mixture of pentane and hexane at room temperature. The solution has a vapor pressure of 258 torr. Pure pentane and hexane have vapor pressures of 425 torr and 151 torr, respectively, at room temperature. What is the mole fraction composition of the mixture? (Assume ideal behavior.)
- A solution contains 4.08 g of chloroform (CHCl3) and 9.29 g of acetone (CH3COCH3). The vapor pressures at 35 °C of pure chloroform and pure acetone are 295 torr and 332 torr, respectively. Assuming ideal behavior, calculate the vapor pressures of each of the components and the total vapor pressure above the solution. The experimentally measured total vapor pressure of the solution at 35 °C is 312 torr. Is the solution ideal? If not, what can you say about the relative strength of chloroform–acetone interactions compared to the acetone–acetone and chloroform–chloroform interactions?
Problem 81
- A solution of methanol and water has a mole fraction of water of 0.312 and a total vapor pressure of 211 torr at 39.9 °C. The vapor pressures of pure methanol and pure water at this temperature are 256 torr and 55.3 torr, respectively. Is the solution ideal? If not, what can be inferred about the relative strengths of the solute–solvent interactions compared to the solute–solute and solvent–solvent interactions?
Problem 82
Problem 83
A glucose solution contains 74.2 g of glucose (C6H12O6) in 455 g of water. Determine the freezing point and boiling point of the solution.
- Calculate the molar mass of an unknown compound given that an aqueous solution containing 17.5 g of the compound in 100.0 g of water has a freezing point of -1.8 °C.
Problem 87
- Calculate the molar mass of an unknown molecular (nonelectrolyte) compound in an aqueous solution containing 35.9 g of the compound in 150.0 g of water with a freezing point of -1.3 °C.
Problem 88
- A solution containing 27.55 mg of an unknown protein per 25.0 mL was found to have an osmotic pressure of 3.22 torr at 25 °C. What is the molar mass of the protein?
Problem 91
- Calculate the osmotic pressure of a solution containing 18.75 mg of hemoglobin in 15.0 mL of solution at 25 °C. The molar mass of hemoglobin is 6.5 x 10^4 g/mol.
Problem 92
Problem 93b
Calculate the freezing point and boiling point of each aqueous solution, assuming complete dissociation of the solute. a. 0.100 m K2S b. 21.5 g of CuCl2 in 4.50⨉102 g water
Problem 93c
Calculate the freezing point and boiling point of each aqueous solution, assuming complete dissociation of the solute. c. 5.5% NaNO3 by mass (in water)
- Is the question formulated correctly for calculating the freezing point and boiling point of each solution, assuming complete dissociation of the solute? For the following: a. 10.5 g FeCl3 in 1.50 * 10^2 g water b. 3.5% KCl by mass (in water) c. 0.150 m MgF2.
Problem 94