CH 12 : Properties of Solution

CH 12 : Properties of Solution

12b-5

Calculate the mole fraction of methanol, CH3OH in a solution of 7.5 g methanol and 245 g H2O

12b-6 Molality = moles of solute/Kg of Solvent

Calculate the molality of each of the following sucrose (C12H22O11) solutions

16.5 g sucrose in 1.35 kg water

3.15 moles of sucrose in 455 g water

0.0356 g of sucrose in 13.0 g water

12b-7

Calculate the number of grams of each solute that must be added to 125 g of water to prepare a 0.400 m solution.

Al(NO3)3

MgCl2

12b-8

An aqueous solution of oxalic acid ( H2C2O4) is 0.568 M and has a density of 1.022 g/mL. What is the MOLALITY of the solution?

12b-9

An aqueous solution of acetic acid (HC2H3O2) is 0.796 M and has a density of 1.004 g/mL. What is the MOLARITY of the solution?

12b-10

A sulfuric acid solution containing 571.6 g of H2SO4 per liter of solution has a density of 1.329 g/mL. Calculate the concentration of this solution in the following units.

1. Mass percent (43.01% H2SO4)
2. Mole fraction H2SO4 (0.122 m H2SO4)
3. Molality (7.70 m H2SO4)
4. Molarity (5.828 M H2SO4)

12b-11

An aqueous solution of propylene glycol, C3H6(OH)2 has a mole fraction = 0.100 for propylene glycol. Calculate the

1. Percent propylene glycol by mass { 2.0% C3H6(OH)2 }
2. Molality of the solution {6.17 m C3H6(OH)2 }

12c-1

Calculate the following for solution of 18.3 grams of glucose, C6H12O6, dissolved in 500 grams of water at 70℃. The vapor pressure of water is 233.7 mmHg.

1. Vapor pressure lowering of the water (0.9 mmHg)
2. Vapor pressure of the solution (232.8 mmHg)

 

12c-2

How many grams of sucrose, C12H22O11, must be added to 3.20102 grams of water to lower the vapor pressure by 1.5 mmHg at 25℃. The vapor pressure of water at 25℃ is 23.8 mmHg. (411 g sucrose)

 

12c-3

An aqueous solution is 0.250 m glucose. What are the boiling and freezing of this solution? (b.p = 100.12℃ f.p = -0.465℃)

 

12c-4

What is the molality of an aqueous glucose solution if its boiling point at atm pressure is 101.27℃? (2.4 amu)

 

12c-5

Camphor, a white solid that melts at 179.5℃, has an unusually large freezing-point depression constant (40℃/m). A 1.07 mg sample of a compound is dissolved in 78.1 mg of camphor. The solution melts at 176.0℃. WHat is the molar mass of the compound?

(160 amu)

12c-6

Each of the following substances is dissolved in a separate 10.0 liters of water: 1.3 mole Na2SO4,  1.5 mole NaCL, 2.0 mole MgCl2, and 2.0 mole KBr. Rank the boiling points of each solution from lowest to highest. (NaCl < Na2SO4 < KBr < MgCl2)

 

12c-7

Rank the freezing point of each of the following solutions from lowest to highest: 0.050 m CaCl2, 0.15 m NaCl, 0.10 m HCl, 0.050 m HC2H3O2,  0.10 m C12H22O11. (NaCl < HCl < CaCl2 < C12H22O11 < HC2H3O2)

 

12c-8

What is the vapor pressure , in mmHg, of a solution made by dissolving 18.3 g of NaCl in 500.0 g of H2O at 70℃? The vapor pressure of water at 70 is 233.7 mmHg. (You should remember that vapor pressure will depend on the total number of dissolved particles) (228.5 mmHg)

 

Osmotic Pressure

 

12d-1

What is the osmotic pressure of a 1.17 M sucrose solution at 25℃? (28.6 atm)

 

12d-2

A solution of an unknown molecular substance in water at 293 K gives rise to an osmotic pressure of 0.566 atm. What is the molarity of the solution? (0.235 M)

 

12d-3

The average osmotic pressure of blood is 7.7 atm at 25℃. What would be the MOLARITY of a glucose, C5H12O6, solution that is isotonic with blood?(0.31 M)

12d-4

A solution prepared by dissolving 120.0 mg of insulin in water and diluting to 5.00 mL produced an osmotic pressure of 12.5 mmHg at 300K. What is the molar mass of insulin? (5990 g/mole)

 

12d-5

Indicate whether the osmotic pressure of a 0.1 M NaCl solution will be less than , the same as, or greater than that of each of the following solutions.

1. 0.1 M NaBr (same)
2. 0.05 M MgCl2 (greater than)
3. 0.1 M MgCl2 (less than)
4. 0.1 M glucose (greater than)

 

12d-6

A 2% by mass sucrose solution and an 8 by mass sucrose solution are separated by a semipermeable membrane.

1. Which sucrose solution exerts the greater osmotic pressure? (8% solution)
2. In what direction does the net flow of water initially occur? (out of 2% solution)
3. Which solution will have a decrease in concentration at equilibrium? ( 8% solution)

 

12d-7

Hexobarbital, used in medicine as a sedative and intravenous anesthetic, is composed of 61.00 percent C, 6.83 percent H, 11.86 percent N, and 20.32 percent O by mass. A sample of 2.505 mg in 10.00 mL of solution has an osmotic pressure of 19.7 torr at 25℃. What is the molecular formula of hexobarbital?(C12H16N2O3)

 

12d-8

A mixture of NaCl and sucrose (C12H22O11) of combined mass 10.2 g dissolved in enough water to make up a 250 mL solution. The osmotic pressure of the solution is 7.32 atm at 23℃. Calculate the mass percent of NaCl in the mixture. (14.2 %)

 

12d-9

Give the type of colloid ( aerosol, foam, emulsion, sol, or gel) that each of the following represents.

1. Rain cloud. (aerosol)
2. Milk of magnesia. (sol)
3. Soapsuds (foam)

Silt in water. (sol)