76) How will the osmotic pressure of an aqueous solution change as evaporation occurs?
A) The osmotic pressure will increase.
B) The osmotic pressure will not change.
C) The osmotic pressure will decrease.
D) The osmotic pressure will increase or decrease until it equals the vapor pressure of water.
77) Assuming that sea water is a 3.5 wt % solution of NaCl in water, calculate its osmotic pressure at
20°C. The density of a 3.5% NaCl solution at 20°C is 1.023 g/mL.
A) 1.0 atm
B) 15 atm
C) 29 atm
D) 100 atm
78) The average osmotic pressure of blood is about 7 atm. Therefore
A) the average blood pressure is about 7 atm.
B) the average pressure inside the body is about 7 atm above the external pressure.
C) a pressure of about 7 atm would be required to prevent osmosis if blood is in contact with pure water
across a semipermeable membrane.
D) All of these are true.
79) Naproxen is a commercially important anti-inflammatory agent that can be isolated from the thyroid
gland. A solution of 1.138 g of naproxen in 25.00 g benzene has an osmotic pressure of 4.00 atm at 20°C.
The density of benzene is 0.8787 g/mL at this temperature. Calculate the molar mass of naproxen,
assuming it remains intact upon dissolution and the density of the solution equals the density of pure
benzene.
A) 176 g/mol
B) 230 g/mol
C) 307 g/mol
D) 3.80 × 105 g/mol
80) A solution of 62.4 g of insulin in enough water to make 1.000 L of solution has an osmotic pressure of
0.305 atm at 25°C. Based on these data, what is the molar mass of insulin?
A) 621 g/mol
B) 5000 g/mol
C) 7570 g/mol
D) 71,900 g/mol
81) A solution of a nonelectrolyte solution contains 30.0 g of solute dissolved in 250.0g of water. The
freezing point of the water is observed to be –2.50˚C. The Kf for water is 1.86 ˚C/m and normal freezing
point of water is 0.00˚C. What is the molar mass of the substance?
A) 335 g/mol
B) 89.5 g/mol
C) 895 g/mol
D) 33.5 g/mol
82) Which drawing above represents the system with the highest entropy?
A) drawing (a)
B) drawing (b)
C) drawing (c)
D) drawing (d)
83) Which drawing above represents the system with the lowest entropy?
A) drawing (a)
B) drawing (b)
C) drawing (c)
D) drawing (d)
84) Which drawing above represents the system with the second lowest entropy?
A) drawing (a)
B) drawing (b)
C) drawing (c)
D) drawing (d)
85) Which drawing above represents the system with the second highest entropy?
A) drawing (a)
B) drawing (b)
C) drawing (c)
D) drawing (d)
Arrows in the energy diagram below represent enthalpy changes occurring in the exothermic formation
of a solution:
ΔHsoln = enthalpy of solution
ΔHsolute-solute = enthalpy change involving solute-solute interactions
ΔHsolute-solvent = enthalpy change involving solute-solvent interactions
ΔHsolvent-solvent = enthalpy change involving solvent-solvent interactions
86) Which arrow represents ΔHsoln?
A) arrow (a)
B) arrow (b)
C) arrow (c)
D) arrow (d)
87) Which arrow represents ΔHsolute-solvent?
A) arrow (a)
B) arrow (b)
C) arrow (c)
D) arrow (d)
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88) Which arrows represent ΔHsolute-solute and ΔHsolvent-solvent?
A) arrow (a) and arrow (b)
B) arrow (a) and arrow (c)
C) arrow (a) and arrow (d)
D) arrow (c) and arrow (d)
89) Which arrow represents ΔHsoln?
A) arrow (a)
B) arrow (b)
C) arrow (c)
D) arrow (d)
90) Which arrow represents ΔHsolute-solvent?
A) arrow (a)
B) arrow (b)
C) arrow (c)
D) arrow (d)
91) Which arrows represent ΔHsolute-solute and ΔHsolvent-solvent?
A) arrow (a) and arrow (b)
B) arrow (a) and arrow (c)
C) arrow (a) and arrow (d)
D) arrow (c) and arrow (d)
92) Which ion-dipole interaction results in the larger (more negative) hydration energy?
A) diagram (a)
B) diagram (b)
C) diagram (c)
D) diagram (d)
93) Which ion-dipole interaction results in the larger (more negative) hydration energy?
A) diagram (a)
B) diagram (b)
C) diagram (c)
D) diagram (d)
94) Drawing (1) shows a system in which an equilibrium exists between dissolved and undissolved gas
particles at P = 1 atm. According to Henry‘s law, if the pressure is increased to 2 atm and equilibrium is
restored, which drawing (2)-(5) best represents the equilibrium at 2 atm?
A) drawing (2)
B) drawing (3)
C) drawing (4)
D) drawing (5)
95) Drawing (1) shows a system in which an equilibrium exists between dissolved and undissolved gas
particles at P = 1 atm. According to Henry‘s law, if the pressure is decreased to 0.5 atm and equilibrium is
restored, which drawing (2)-(5) best represents the equilibrium at 0.5 atm?
A) drawing (2)
B) drawing (3)
C) drawing (4)
D) drawing (5)
96) Drawing (1) shows the equilibrium vapor pressure of a pure liquid. Which drawing (2)-(5) represents
the equilibrium vapor pressure when a nonvolatile solute is dissolved in the liquid?
A) drawing (2)
B) drawing (3)
C) drawing (4)
D) drawing (5)
97) Drawings (1) and (2) show the equilibrium vapor pressures of two pure liquids. Which drawing (3)–
(6) represents the equilibrium vapor pressure of a solution made by mixing equal moles of each liquid?
A) drawing (3)
B) drawing (4)
C) drawing (5)
D) drawing (6)
The following diagram shows a close-up view of the vapor pressure curves for a pure solvent and a
solution containing a nonvolatile solute dissolved in this solvent.
98) Which curve is the solvent and what happens to the vapor pressure when the solute is dissolved in
the solvent?
A) Curve (a) is the solvent and the vapor pressure decreases.
B) Curve (a) is the solvent and the vapor pressure increases.
C) Curve (b) is the solvent and the vapor pressure decreases.
D) Curve (b) is the solvent and the vapor pressure increases.
99) Which curve is the solvent and what happens to the boiling point when the solute is dissolved in the
solvent?
A) Curve (a) is the solvent and the boiling point decreases.
B) Curve (a) is the solvent and the boiling point increases.
C) Curve (b) is the solvent and the boiling point decreases.
D) Curve (b) is the solvent and the boiling point increases.
100) The following diagram shows a close-up view of the vapor pressure curves for two pure liquids and
two different solutions composed of these two liquids. Which curves represent pure liquids and which
curves represent the solutions?
A) Curves (a) and (b) are the pure liquids and curves (c) and (d) are the solutions.
B) Curves (a) and (c) are the pure liquids and curves (b) and (d) are the solutions.
C) Curves (a) and (d) are the pure liquids and curves (b) and (c) are the solutions.
D) Curves (c) and (d) are the pure liquids and curves (a) and (b) are the solutions.
101) Drawing (1) shows a nonequilibrium system comprised of pure water separated from an aqueous
solution by a semipermeable membrane. Shaded spheres represent solute particles and unshaded spheres
represent water molecules. Which drawing (2)-(5) represents this system after equilibrium is reached?
A) drawing (2)
B) drawing (3)
C) drawing (4)
D) drawing (5)
102) Two beakers, one with pure water (light gray) and the other with an aqueous solution of KBr (dark
gray), are placed in a closed container represented by drawing (a). Which of the drawings (a)-(d)
represents what the beakers will look like after a substantial amount of time has passed?
A) drawing (a)
B) drawing (b)
C) drawing (c)
D) drawing (d)
A phase diagram of temperature versus composition for a mixture of the two volatile liquids octane (bp =
and decane (bp = 126°C) is shown.
103) Assume that you start with a mixture containing 0.80 mol of decane and 0.20 mol of octane, what
region of the diagram corresponds to liquid?
A) region a
B) region b
C) region c
D) regions a and c
104) Assume that you start with a mixture containing 0.80 mol of decane and 0.20 mol of octane, what
region of the diagram corresponds to vapor?
A) region a
B) region b
C) region c
D) regions a and c
A phase diagram of temperature versus composition for a mixture of the two volatile liquids octane (bp =
and decane (bp = 126°C) is shown.
105) Assume that you start with a mixture containing 0.80 mol of decane and 0.20 mol of octane, at what
approximate temperature will the mixture begin to boil?
A) temperature at point a
B) temperature at point b
C) temperature at point d
D) temperature at point f
106) Assume that you start with a mixture containing 0.80 mol of decane and 0.20 mol of octane, what is
the liquid composition at the boiling point?
A) 100% decane
B) composition at point b
C) composition at point c
D) composition at point e
107) Assume that you start with a mixture containing 0.80 mol of decane and 0.20 mol of octane, what is
the vapor composition at the boiling point?
A) 100% decane
B) composition at point b
C) composition at point c
D) composition at point e
108) Assume that the vapor at point c is condensed and reboiled. What is the liquid composition of the
condensed vapor prior to reboiling?
A) 100% decane
B) composition at point b
C) composition at point d
D) composition at point e
109) Assume that the vapor at point c is condensed and reboiled. What is the vapor composition during
reboiling?
A) 100% decane
B) composition at point b
C) composition at point c
D) composition at point e
110) Assume that the vapor at point c is condensed and reboiled. What is the boiling point?
A) temperature at point b
B) temperature at point c
C) temperature at point d
D) temperature at point f
111) What is the approximate boiling temperature of a mixture that is 0.70 XA and 0.30 XB?
A) 50°C
B) 75°C
C) 95°C
D) 100°C
112) What is the approximate vapor composition above a boiling solution that is 0.70 XA and 0.30 XB?
A) 0.70 XA, 0.30 XB
B) 0.50 XA, 0.50 XB
C) 0.30 XA, 0.70 XB
D) 0 XA, 1.00 XB
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113) What is the approximate boiling temperature of the liquid formed from the condensation of the
vapor above a boiling solution that is 0.70 XA and 0.30 XB?
A) 50°C
B) 55°C
C) 90°C
D) 100°C
114) At 80°C, pure liquid A has a vapor pressure of 700 mm Hg and pure liquid B has a vapor pressure of
940 mm Hg. What is XA for a solution of A and B with a normal boiling point of
A) 0.25
B) 0.50
C) 0.75
D) A solution of A and B cannot boil at 80°C.
12.2 Algorithmic Questions
1) A gold ring is an example of a ________ solution.
A) gas/gas
B) liquid/solid
C) solid/lliquid
D) solid/solid
2) Which is not a solution?
A) sterling silver
B) fog
C) hydrochloric acid
D) coffee
3) KI does not dissolve well in nonpolar solvents because