work numbers
25
27
30
34
38
and
42 please
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Done COLLIGATIVE EXERCI...
17. You make a saturated solution of NaCl at 25 °C.
No solid is present in the beaker holding the solu-
tion. What can be done to increase the amount of
dissolved NaCl in this solution? (See
Figure 13.11.)
(a) Add more solid NaCl.
(b) Raise the temperature of the solution.
(c) Raise the temperature of the solution, and add
some NaCl.
(d) Lower the temperature of the solution, and
add some NaCI.
18. Some lithium chloride, LiCI, is dissolved in
100 ml. of water in one beaker, and some Li,So,
is dissolved in 100 ml. of water in another beaker.
Both are at 10 °C, and both are saturated solu-
tions; some solid remains undissolved in each
beaker Describe what you would observe as the
temperature is raised. The following data are avail-
able to you from a handbook of chemistry:
Le Chatelier's Principle
(See Section 13.3.)
23. A sealed flask contains water and oxygen gas
at 25 °C. The O, gas has a partial pressure of
1.5 atm.
(a) What is the concentration of O, in the water?
(b) If the pressure of O, in the flask is raised to
1.7 atm, what happens to the amount of dis-
solved O,1 What happens to the amount of
dissolved O, when the pressure of O, gas
drops to 1.0 atm?
24. Butane, CH has been suggested as the refrig-
erant in household compressors such as those
found in air conditioners.
(a) To what extent is butane soluble in water?
Calculate the butane concentration in water
if the pressure of the gas is 0.21 atm. (ky=
0.0011 mol/kg bar at 25 C)
(b) If the pressure of butane is increased to
1.0 atm, does the butane concentration
increase or decrease?
Solubility (g/100 mL)
Compound
Li so
10 °C
40 °C
Raoult's Law
(See Section 13.4 and Example 13.4.)
35.5
33.7
Lici
74.5
89.8
A 35.0-g sample of ethylene glycol, HOCH,CH,OH,
is dissolved in 500.0 g of water. The vapor pressure
of water at 32 "C is 35.7 mm Hg. What is the vapor
pressure of the water-ethylene glycol solution at
32 C? (Ethylene glycol is nonvolatile)
Henry's Law
(See Section 13.3 and Example 13.3.)
19. The panial pressure of O, in your lungs varies
from 25 mm Hg to 40 mm Hg. What mass ofo,
can dissolve in 1.0 L of water at 25 *Cif the
partial pressure of O, is 40 mm Hg?
20. The Henry's law constant for O, in water at 25 "C
is given in Table 13.2. Which of the following is
a reasonable constant when the temperature is
50 °C? Explain the reason for your choice.
(a) 6.7 x 10-+ mol/kg bar
(b) 2.6 k 10 mol/kg bar
(c) 1.3 X 10 mol/kg bar
(d) 6.4 * 10 2 mol/kg bar
21. An unopened soda can has an aqueous CO, con-
centration of 0.0506 m at 25 °C. What is the pres-
sure of CO, gas in the can?
26. Urea, (NH,),CO, which is widely used in fertil-
izers and plastics, is quite soluble in water. If you
dissolve 9.00 g of urea in 10.0 mL of water, what
is the vapor pressure of the solution at 24 *C?
Assume the density of water is 1.00 g/mL.
Pure ethylene glycol, HOCH,CH,OH, is added to
2.00 kg of water in the cooling system of a ca.
The vapor pressure of the water in the system
when the temperature is 90 "C is 457 mm 1lg.
What mass of glycol was added? (Assume the
solution is ideal. See Appendix G for the vapor
pressure of water.)
22. Hydrogen gas has a llenry's law constant of 7.8 x
10 mol/kg bar at 25 °C when dissolving in
water. If the total pressure of gas (H, gas plus
water vapor) over water is 1.00 bar, what is the
concentration of II, in the water in grams per mil-
liliter? (See Appendix G for the vapor pressure of
water.)
28. Pure iodine (105 g) is dissolved in 325 g of CCI,
at 65 °C. Given that the vapor pressure of CCl,
at this temperature is 531 mm Hg, what is the
vapor pressure of the CCI,-I, solution at 65 *C?
(Assume that I, does not contribute to the vapor
pressure.)
Study Questions
601
Boiling Point Elevation
(See Section 13.4 and Hxample 13.5.)
29. What is the boiling point of a solution containing
0.200 mol of a nonvolatile solute in 125 g of
benzene (C,H.)?
What is the boiling point of a solution composed
of 15.0 g of urea (NH,).CO, in 0.500 kg of water?
31. What is the boiling point of a solution composed
of 15.0 g of CHCI, and 0.515 g of the nonvolatile
solute acenaphthene, CH, a component of
39. An aqueous solution containing 1.00 g of bovine
insulin (a protein, not ionized) per liter has an
Osmotic pressure of 3.1 mm HIg at 25 "C. Calcu-
late the molar mass of bovine insulin.
40. Calculate the osmotic pressure of a 0.01 20 M solu-
tion of NaCl in water at 0 "C. Assume the van't
Hoff factor, i, is 1.94 for this solution.
Colligative Properties and Molar Mass Determination
(See Section 13.4 and Examples 13.8 and 13.9.)
41. You add 0.255 g of an orange, crystalline com-
pound whose empirical formula is CoHFe to
11.12 g of benzene. The boiling point of the
benzene rises from 80. 10 C to 80.26 °C. What
are the molar mass and molecular formula of the
compound?
coal tar?
32. A solution of glygerol. C,H.(OH), in 735 g of
water has a boiling point of 104.4 C at a pressure
of 760 mm Hg. What is the mass of glycerol in the
solution? What is the mole fraction of the solute?
Freezing Point Depression
(See Section 13.4 and Example 13.6.)
33. A mixture of ethanol, CH,OH, and water has a
freezing point of -16.0 *C.
(a) What is the molality of the alcohol?
(b) What is the weight percent of alcohol in the
42 Butylated hydroxyanisole (BHA) is used in mar-
garine and other fats and oils. (It is used as an
antioxidant and prolongs the shelf life of the
food.) What is the molar mass of BHA if 0.640 g
of the compound, dissolved in 25.0 g of chloro-
form, produces a solution whose boiling point is
62.22 °C?
solution?
wa Randa
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15 givenjin Table 13.2. Which of the following is
a reasonable constant when the temperature is
50 "CI Explain the reason for your choice.
(a) 6.7 x 10- mol/kg- bar
(b) 2.6 10- mol/kg bar
(c) 1.3 K 10'mol/kg-bar
(d) 6.4 k 10-2 mol/kg bar
Assume the density of water is 1.00 g/mL.
Pure ethylene glycol, HOCH,CH,OH, is added to
2.00 kg of water in the cooling system of a car.
The vapor pressure of the water in the system
when the temperature is 90 *C is 457 mm lg.
What mass of glycol was added? (Assume the
solution is ideal. See Appendix G for the vapor
pressure of water.)
21. An unopened soda can has an aqueous CO, con-
centration of 0.0506 m at 25 °C. What is the pres-
sure of CO, gas in the can?
28. Pure iodine (105 g) is dissolved in 325 g of CCI,
at 65 °C. Given that the vapor pressure of CCl,
at this temperature is 531 mm Hg, what is the
vapor pressure of the CCI,-1, solution at 65 *C?
(Assume that I, does not contribute to the vapor
pressure.)
22. Hydrogen gas has a Ilenry's law constant of 7.8 x
10- mol/kg bar at 25 "C when dissolving in
water. If the total pressure of gas (H; gas plus
water vapor) over water is 1.00 bar, what is the
concentration of II, in the water in grams per mil-
liliter? (See Appendix G for the vapor pressure of
water.)
Study Questions
601
Boiling Point Elevation
(See Section 13.4 and Eranple 13.5.)
29. What is the boiling point of a solution containing
0.200 mol of a nonvolatile solute in 125 g of
benzene (CH,)
What is the boiling point of a solution composed
of 15.0 g of urea, (NH,).CO, in 0.500 kg of water?
31. What is the boiling point of a solution composed
of 15.0 g of CHCI, and 0.515 g of the nonvolatile
solute acenaphthene, CH1o, a component of
39. An aqueous solution containing 1.00 g of bovine
insulin (a protein, not ionized) per liter has an
Osmotic pressure of 3.1 mm Hg at 25 °C. Calcu-
late the molar mass of bovine insulin.
40. Calculate the osmotic pressure of a 0.0120M solu-
tion of NaCl in water at 0 °C. Assume the van't
Hoff factor, i, is 1.94 for this solution.
Colligative Properties and Molar Mass Determination
(See Section 13.4 and Examples 13.8 and 13.9)
41. You add 0.255 g of an orange, crystalline com-
pound whose empirical formula is CoH,Fe to
11.12 g of benzene. The boiling point of the
benzene rises from 80. 10 °C to 80.26 °C. What
are the molar mass and molecular formula of the
compound?
coal tar?
32. A solution of glyderol. C,He(OH), in 735 g of
water has a boiling point of 104.4 "C at a pressure
of 760 mm Hg, What is the mass of glycerol in the
solution? What is the mole fraction of the solute?
Freezing Point Depression
(See Section 13.4 and Example 13.6.)
33. A mixture of ethanol, CH,OH, and water has a
freezing point of -16.0 °C.
(a) What is the molality of the alcohol?
(b) What is the weight percent of alcohol in the
solution?
Butylated hydroxyanisole (BHA) is used in mar-
garine and other fats and oils. (It is used as an
antioxidant and prolongs the shelf life of the
food.) What is the molar mass of BHA if 0.640 g
of the compound, dissolved in 25.0 g of chloro-
form, produces a solution whose boiling point is
62.22 °C?
43. Benzyl acetate is one of the active components of
oil of jasmine. If 0.125 g of the compound is
added to 25.0 g of chloroform (CHCI,), the
boiling point of the solution is 61.82 "C. What is
the molar mass of benzyl acetate?
34) Some ethylene glycol, HOCH,CH,OH, is added
to your car's cooling system along with 5.0 kg of
water. If the freezing point of the water-glycol solu-
tion is –15.0 *C. what mass of HOCH,CH,OH
must have been added?
35. You dissolve 15.0 g of sucrose, CHOue in a cup
of water (225 g). What is the freezing point of the
solution?
44. Anthracene, a hydrocarbon obtained from coal,
has an empirical formula of CHs. To find its
molecular formula, you dissolve 0.500 g in 30.0 g
of benzene. The boiling point of pure benzene
is 80.10 °C, whereas the solution has a boiling
point of 80.34 °C. What is the molecular formula
of anthracene?
36. A typical bottle of wine consists of an 11% solu-
tion (by weight) of ethanol (C,H,OH) in water.
If the wine is chilled to -20 °C, will the solution
begin to freeze?
45. An aqueous solution contains 0.180 g of an
unknown, nonionic solute in 50.0 g of water, The
solution freezes at -0.040 C. What is the molar
Osmosis
(See Section 13.4 and Example 13.7.)
mass of the solute?
37. An aqueous solution contains 3.00% phenylala-
nine (C,HNO,) by mass. (Phenylalanine is non-
ionic and nonvolațile) Find the following:
(a) the freezing point of the solution
(b) the boiling point of the solution
(c) the osmotic pressure of the solution at 25 °C
In your view, which of these values is most easily
measurable in the laboratory?
46. Aluminon, an organic compound, is used as a
reagent to test for the presence of the aluminum
ion in aqueous solution. A solution of 2.50 g of
aluminon in 50.0 g of water freezes at -0.197 C.
What is the molar mass of aluminon?
Colligative Properties of lonic Compounds
(See Section 13.4 and Example 13, 10.)
47. If 52.5 g of LiF is dissolved in 306 g of water, what
is the expected freezing point of the solution?
(Assume the van't Hoff factor, i, for LiF is 2.)
Estimate the osmotic pressure of human blood at
37 °C. Assume blopd is isotonic with a 0.154 M
NaCl solution, and assume the van't Hoff factor, i,
is 1,90 for NaCI.
602
CHAPTER 13/ Solutions and Their Behavior