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Problem 49c
The density of acetonitrile (CH3CN) is 0.786 g/mL and the density of methanol (CH3OH) is 0.791 g/mL. A solution is made by dissolving 22.5 mL of CH3OH in 98.7 mL of CH3CN. (c) Assuming that the volumes are additive, what is the molarity of CH3OH in the solution?
Problem 50a
The density of toluene (C7H8) is 0.867 g/mL, and the density of thiophene (C4H4S) is 1.065 g/mL. A solution is made by dissolving 8.10 g of thiophene in 250.0 mL of toluene. (a) Calculate the mole fraction of thiophene in the solution.
Problem 50b
The density of toluene (C7H8) is 0.867 g/mL, and the density of thiophene (C4H4S) is 1.065 g/mL. A solution is made by dissolving 8.10 g of thiophene in 250.0 mL of toluene. (b) Calculate the molality of thiophene in the solution.
Problem 51a
Calculate the number of moles of solute present in each of the following aqueous solutions: (a) 600 mL of 0.250 M SrBr2,
Problem 51b
Calculate the number of moles of solute present in each of the following aqueous solutions: (b) 86.4 g of 0.180 m KCl,
Problem 51c
Calculate the number of moles of solute present in each of the following aqueous solutions: (c) 124.0 g of a solution that is 6.45% glucose (C6H12O6) by mass.
Problem 52a
Calculate the number of moles of solute present in each of the following solutions: (a) 255 mL of 1.50 M HNO3(aq),
Problem 52b,c
Calculate the number of moles of solute present in each of the following solutions: (b) 50.0 mg of an aqueous solution that is 1.50 m NaCl, (c) 75.0 g of an aqueous solution that is 1.50% sucrose (C12H22O11) by mass.
Problem 53b
Describe how you would prepare each of the following aqueous solutions, starting with solid KBr: (b) 125 g of 0.180 m KBr,
Problem 53c
Describe how you would prepare each of the following aqueous solutions, starting with solid KBr: (c) 1.85 L of a solution that is 12.0% KBr by mass (the density of the solution is 1.10 g/mL)
Problem 53d
Describe how you would prepare each of the following aqueous solutions, starting with solid KBr: (d) a 0.150 M solution of KBr that contains just enough KBr to precipitate 16.0 g of AgBr from a solution containing 0.480 mol of AgNO3.
Problem 54a
Describe how you would prepare each of the following aqueous solutions: (a) 1.50 L of 0.110 M 1NH422SO4 solution, starting with solid 1NH422SO4;
Problem 54c
Describe how you would prepare each of the following aqueous solutions: (c) 1.20 L of a solution that is 15.0% Pb(NO3)2 by mass (the density of the solution is 1.16 g/mL), starting with solid solute;
Problem 55
Commercial aqueous nitric acid has a density of 1.42 g/mL and is 16 M. Calculate the percent HNO3 by mass in the solution.
Problem 56
Commercial concentrated aqueous ammonia is 28% NH3 by mass and has a density of 0.90 g/mL. What is the molarity of this solution?
Problem 56
Commercial concentrated aqueous ammonia is 28% NH3 by mass and has a density of 0.90 g/mL. What is the molarity of this solution?
Problem 57a
Brass is a substitutional alloy consisting of a solution of copper and zinc. A particular sample of red brass consisting of 80.0 % Cu and 20.0 % Zn by mass has a density of 8750 kg/m3. (a) What is the molality of Zn in the solid solution?
Problem 57b
Brass is a substitutional alloy consisting of a solution of copper and zinc. A particular sample of red brass consisting of 80.0 % Cu and 20.0 % Zn by mass has a density of 8750 kg/m3. (b) What is the molarity of Zn in the solution?
Problem 58b
Caffeine (C8H10N4O2) is a stimulant found in coffee and tea. If a solution of caffeine in the solvent chloroform (CHCl3) has a concentration of 0.0500 m, calculate (b) the mole fraction of caffeine in the solution.
- During a person’s typical breathing cycle, the CO2 concentration in the expired air rises to a peak of 4.6% by volume. (b) What is the molarity of the CO2 in the expired air at its peak, assuming a body temperature of 37 °C?
Problem 59
Problem 60a
Breathing air that contains 4.0 % by volume CO2 over time causes rapid breathing, throbbing headache, and nausea, among other symptoms. What is the concentration of CO2 in such air in terms of (a) mol percentage,
Problem 60b
Breathing air that contains 4.0 % by volume CO2 over time causes rapid breathing, throbbing headache, and nausea, among other symptoms. What is the concentration of CO2 in such air in terms of (b) molarity, assuming 1 atm pressure and a body temperature of 37 °C?
- You make a solution of a nonvolatile solute with a liquid solvent. Indicate whether each of the following statements is true or false. (a) The freezing point of the solution is higher than that of the pure solvent. (b) The freezing point of the solution is lower than that of the pure solvent.
Problem 61
Problem 62a
You make a solution of a nonvolatile solute with a liquid solvent. Indicate if each of the following statements is true or false. (a) The freezing point of the solution is unchanged by addition of the solvent.
Problem 62b
You make a solution of a nonvolatile solute with a liquid solvent. Indicate if each of the following statements is true or false. (b) The solid that forms as the solution freezes is nearly pure solute.
Problem 62d,e
You make a solution of a nonvolatile solute with a liquid solvent. Indicate if each of the following statements is true or false. (d) The boiling point of the solution increases in proportion to the concentration of the solute. (e) At any temperature, the vapor pressure of the solvent over the solution is lower than what it would be for the pure solvent.
- Consider two solutions, one formed by adding 10 g of glucose (C6H12O6) to 1 L of water and the other formed by adding 10 g of sucrose (C12H22O11) to 1 L of water. Calculate the vapor pressure for each solution at 20 °C; the vapor pressure of pure water at this temperature is 17.5 torr.
Problem 63
- The vapor pressure of pure water at 60 °C is 149 torr. The vapor pressure of water over a solution at 60 °C containing equal numbers of moles of water and ethylene glycol (a nonvolatile solute) is 67 torr. Is the solution ideal according to Raoult's law?
Problem 64
- (a) Calculate the vapor pressure of water above a solution prepared by adding 22.5 g of lactose (C12H22O11) to 200.0 g of water at 338 K. (Vapor–pressure data for water are given in Appendix B.)
Problem 65
- (b) Calculate the mass of ethylene glycol (C2H6O2) that must be added to 1.00 kg of ethanol (C2H5OH) to reduce its vapor pressure by 10.0 torr at 35 °C. The vapor pressure of pure ethanol at 35 °C is 1.00 x 10^2 torr.
Problem 66