Question 1

Which statement regarding the fractional distillation of two substances is not correct?

Accepted Answer

A)  The substance with the lower boiling point has a higher concentration in the vapor than in the liquid. 
B)  The boiling point of the mixture is not constant, changing as the distillation progresses. 
C)  The substance with the higher vapor pressure has a higher concentration in the vapor than in the liquid. 
D)  The mole ratio of the two substances in the vapor is not the same as it is in the liquid. 
E)  Raoult's law does not apply to mixtures of volatile components. 
A)  The substance with the lower boiling point has a higher concentration in the vapor than in the liquid. 
B)  The boiling point of the mixture is not constant, changing as the distillation progresses. 
C)  The substance with the higher vapor pressure has a higher concentration in the vapor than in the liquid. 
D)  The mole ratio of the two substances in the vapor is not the same as it is in the liquid. 
E)  Raoult's law does not apply to mixtures of volatile components. E

Question 2

Describe how the data obtained by a measurement of osmotic pressure can be used to determine the molar mass of a compound.

Accepted Answer

The concentration (molarity) of particles in a solution can be determined from an osmotic pressure measurement because F1F1F1S1F1F1F10 = iMRT where F1F1F1S1F1F1F10 = osmotic pressure, i = van't Hoff factor, M = molarity of the compound in solution, R = gas constant, and T = temperature in K. iM is the concentration of the particles, as the van't Hoff factor is the ratio of the moles of particles to the moles of the compound. For example, 1 mole of NaCl produces 2 moles of particles, 1 mole of Na+ and 1 mole of Cl^-. So, to determine the molar mass of the compound, the van't Hoff factor must be determined. If the solution does not conduct electricity, then the van't Hoff factor = 1 because the compound in solution does not dissociate into ions. Consequently, once the molarity of the solution is known, the molar mass can be obtained from the following equation: molarity = ( mass/molar mass)/volume of solution, because the solution of a known volume is prepared with a known mass of the compound.

Question 3

Calculate the minimum pressure that must be applied to achieve reverse osmosis of 0.504 M NaCl at 22F1F1F1S1F1F1F10C.

Accepted Answer

A)  0.906 atm 
B)  92.2 atm 
C)  0.909 atm 
D)  12.2 atm 
E)  24.4 atm 
A)  0.906 atm 
B)  92.2 atm 
C)  0.909 atm 
D)  12.2 atm 
E)  24.4 atm E

Question 4

What physical property is used to separate the hydrocarbon components in petroleum (crude oil)?

Accepted Answer

A)  melting point 
B)  density 
C)  boiling point 
D)  molar mass 
E)  viscosity 
A)  melting point 
B)  density 
C)  boiling point 
D)  molar mass 
E)  viscosity

Question 5

A solution is prepared by adding 0.300 mol glucose, which is not volatile, to 4.50 mol water. What is the vapor pressure of this solution at 25°C given that the vapor pressure of pure water is 23.8 torr?

Accepted Answer

A)  9.38 torr 
B)  22.3 torr 
C)  23.4 torr 
D)  1.49 torr 
E)  22.5 torr 
A)  9.38 torr 
B)  22.3 torr 
C)  23.4 torr 
D)  1.49 torr 
E)  22.5 torr

Question 6

Isopropyl alcohol has a boiling point of 82.3°C. Solutions of isopropyl alcohol in water have normal boiling points less than 100°C. Is this observation consistent with the following equation? Explain. F1F1F1S1F1F1F10Tb = iKbm

Accepted Answer

A)  No, boiling point elevation only pertains to ionic solutes. 
B)  No, boiling point elevation only pertains to nonvolatile solutes. 
C)  Yes, boiling point depression occurs for all solutions. 
D)  Yes, the boiling point depression constant for isopropyl alcohol is large. 
E)  No, isopropyl alcohol can hydrogen bond with water. 
A)  No, boiling point elevation only pertains to ionic solutes. 
B)  No, boiling point elevation only pertains to nonvolatile solutes. 
C)  Yes, boiling point depression occurs for all solutions. 
D)  Yes, the boiling point depression constant for isopropyl alcohol is large. 
E)  No, isopropyl alcohol can hydrogen bond with water.

Question 7

A solution of 5.00 g of sodium chloride in 1.00 kg of water has a freezing point of -0.299°C. What is the actual van't Hoff factor for this salt at this concentration compared to the ideal one of 2? Kf(water) = 1.86°C/m

Accepted Answer

A)  1.88 
B)  1.98 
C)  1.93 
D)  1.83 
E)  1.94 
A)  1.88 
B)  1.98 
C)  1.93 
D)  1.83 
E)  1.94

Question 8

What is the molality of a solution produced by dissolving 14.40 g of LiCl (42.39 g/mol) in water to make 0.104 L of solution with a density of 1.102 g/mL?

Accepted Answer

A)  0.340 m 
B)  3.39 m 
C)  3.27 m 
D)  3.74 m 
E)  2.96 m 
A)  0.340 m 
B)  3.39 m 
C)  3.27 m 
D)  3.74 m 
E)  2.96 m

Question 9

A physiological saline solution is 0.92% NaCl by mass. What is the osmotic pressure of such a solution at a body temperature of 37°C?

Accepted Answer

A)  8.0 atm 
B)  3.9 atm 
C)  2.3 atm 
D)  4.3 atm 
E)  4.1 atm 
A)  8.0 atm 
B)  3.9 atm 
C)  2.3 atm 
D)  4.3 atm 
E)  4.1 atm

Question 10

The freezing point of a 0.0925 m solution of ammonium chloride was found to be -0.325°C. What is the actual van't Hoff factor for this salt at this concentration compared to the ideal one of 2? Kf(water) = 1.86°C/m

Accepted Answer

A)  1.89 
B)  1.95 
C)  1.90 
D)  1.80 
E)  1.97 
A)  1.89 
B)  1.95 
C)  1.90 
D)  1.80 
E)  1.97

Question 11

A newspaper article suggested using a fertilizer such as ammonium sulfate or ammonium nitrate to lower the melting point of ice on sidewalks because many of the deicing salts can damage lawns and sidewalks. Which of the following compounds would give the largest freezing point depression when 100 g of the compound are dissolved in 1 kg of solvent?

Accepted Answer

A)  NH4NO3 (80.1 g/mol) 
B)  (NH4)2SO4 (132.1 g/mol) 
C)  MgSO4 (120.4 g/mol) 
D)  CaCl2 (111.0 g/mol) 
E)  MgCl2 (95.2 g/mol) 
A)  NH4NO3 (80.1 g/mol) 
B)  (NH4)2SO4 (132.1 g/mol) 
C)  MgSO4 (120.4 g/mol) 
D)  CaCl2 (111.0 g/mol) 
E)  MgCl2 (95.2 g/mol)

Question 12

A 300-mg sample of caffeine was dissolved in 10.0 g of camphor (Kf = 39.7°C/m), decreasing the freezing point of camphor by 3.07°C. What is the molar mass of caffeine?

Accepted Answer

A)  47.0 g/mol 
B)  194 g/mol 
C)  388 g/mol 
D)  94.0 g/mol 
E)  97.0 g/mol 
A)  47.0 g/mol 
B)  194 g/mol 
C)  388 g/mol 
D)  94.0 g/mol 
E)  97.0 g/mol

Question 13

You like boiled eggs for breakfast, but they take too long to cook, and you are always late to your early morning class. Lucky you! You have learned that adding table salt, NaCl (58.4 g/mol, 2.16 g/cm3), to water (Kb = 0.52oC/m) increases the temperature at which it boils. You figure that you can cook eggs faster at a higher temperature in boiling salty water! What increase in the boiling point do you expect if you add 4 tablespoons (1 tbsp = 14.8 cm3) of salt to 16 oz of water (474 mL)?

Accepted Answer

A)  14°C 
B)  4.8°C 
C)  28°C 
D)  3.0°C 
E)  8.4°C 
A)  14°C 
B)  4.8°C 
C)  28°C 
D)  3.0°C 
E)  8.4°C

Question 14

Portable lanterns and stoves used for camping often use a mixture of hydrocarbons for fuel. One such hydrocarbon is an alkane called n-pentane. These lanterns and stoves are often difficult to light on a cold day because the fuel has a low vapor pressure at low temperatures. Determine the vapor pressure of n-pentane on a night when the temperature is 0.0oC. The enthalpy of vaporization of n-pentane is 27.6 kJ/mol, and its boiling point is 36.0°C.

Accepted Answer

A)  228 torr 
B)  367 torr 
C)  184 torr 
D)  479 torr 
E)  209 torr 
A)  228 torr 
B)  367 torr 
C)  184 torr 
D)  479 torr 
E)  209 torr

Question 15

Identify the following statement as true or false and choose the correct explanation. "For solutions with the same molarity at the same temperature, the pressure needed for reverse osmosis of a sodium chloride solution will always be less than the pressure needed for a calcium chloride solution."

Accepted Answer

A)  True, because the molar mass of sodium chloride is smaller. 
B)  True, because the van't Hoff factor is smaller for sodium chloride. 
C)  False, because the van't Hoff factor is smaller for sodium chloride. 
D)  False, because the van't Hoff factor is larger for sodium chloride. 
E)  True, because the van't Hoff factor is larger for sodium chloride. 
A)  True, because the molar mass of sodium chloride is smaller. 
B)  True, because the van't Hoff factor is smaller for sodium chloride. 
C)  False, because the van't Hoff factor is smaller for sodium chloride. 
D)  False, because the van't Hoff factor is larger for sodium chloride. 
E)  True, because the van't Hoff factor is larger for sodium chloride.

Question 16

Gasoline is primarily a mixture of hydrocarbons and is sold with an octane rating that is based on a comparison with the combustion properties of isooctane. Gasoline usually contains an isomer of isooctane called tetramethylbutane (C8H18), which has an enthalpy of vaporization of 43.3 kJ/mol and a boiling point of 106.5°C. Determine the vapor pressure of tetramethylbutane on a very hot summer day when the temperature is 38°C.

Accepted Answer

A)  80.0 torr 
B)  36.7 torr 
C)  67.8 torr 
D)  47.9 torr 
E)  89.3 torr 
A)  80.0 torr 
B)  36.7 torr 
C)  67.8 torr 
D)  47.9 torr 
E)  89.3 torr

Question 17

A solution is prepared by adding 1.50 mol glucose, which is not volatile, to 3.50 mol water. What is the vapor pressure of this solution at 25°C given that the vapor pressure of pure water is 23.8 torr?

Accepted Answer

A)  7.00 torr 
B)  16.7 torr 
C)  10.2 torr 
D)  7.14 torr 
E)  34.0 torr 
A)  7.00 torr 
B)  16.7 torr 
C)  10.2 torr 
D)  7.14 torr 
E)  34.0 torr

Question 18

Ethylene glycol is used in automobile radiators as an antifreeze. What will the freezing point of an antifreeze solution be if 2.5 L of ethylene glycol are mixed together with 2.5 L of water? The following information may be helpful to you. Ethylene glycol has a very low vapor pressure and is essentially nonvolatile. molar mass of ethylene glycol = 62.1 g/mol
Van't Hoff factor = 1
Density of ethylene glycol = 1.11 g/mL
Density of water = 1.00 g/mL
Kf for water = 1.86°C kg/mol

Accepted Answer

A)  -39°C 
B)  -16°C 
C)  -1.6°C 
D)  -33°C 
E)  -24°C 
A)  -39°C 
B)  -16°C 
C)  -1.6°C 
D)  -33°C 
E)  -24°C

Question 19

Which statement regarding osmotic pressure is not correct? Osmotic pressure __________

Accepted Answer

A)  increases with increasing temperature. 
B)  increases with increasing molar concentration of solute. 
C)  is greater for 0.1 M Na2SO4 than for 0.1 M NaCl. 
D)  depends on the value of the gas constant R. 
E)  is the same for solutions with the same mass percent of solute. 
A)  increases with increasing temperature. 
B)  increases with increasing molar concentration of solute. 
C)  is greater for 0.1 M Na2SO4 than for 0.1 M NaCl. 
D)  depends on the value of the gas constant R. 
E)  is the same for solutions with the same mass percent of solute.

Question 20

A solution is made by dissolving 100 g of essentially nonvolatile ethylene glycol (C2H6O2) in 500 g of water. What is the resulting freezing point of the solution (Kf = 1.86°C/m)?

Accepted Answer

A)  -5.99°C 
B)  -1.86°C 
C)  -0.372°C 
D)  -1.61°C 
E)  -3.23°C 
A)  -5.99°C 
B)  -1.86°C 
C)  -0.372°C 
D)  -1.61°C 
E)  -3.23°C

Which statement regarding the fractional distillation of two substances is not correct?

Describe how the data obtained by a measurement of osmotic pressure can be used to determine the molar mass of a compound.

Calculate the minimum pressure that must be applied to achieve reverse osmosis of 0.504 M NaCl at 22C.

What physical property is used to separate the hydrocarbon components in petroleum (crude oil)?

A solution is prepared by adding 0.300 mol glucose, which is not volatile, to 4.50 mol water. What is the vapor pressure of this solution at 25°C given that the vapor pressure of pure water is 23.8 torr?

Isopropyl alcohol has a boiling point of 82.3°C. Solutions of isopropyl alcohol in water have normal boiling points less than 100°C. Is this observation consistent with the following equation? Explain. T_b = iK_bm

A solution of 5.00 g of sodium chloride in 1.00 kg of water has a freezing point of -0.299°C. What is the actual van't Hoff factor for this salt at this concentration compared to the ideal one of 2? K_f(water) = 1.86°C/m

What is the molality of a solution produced by dissolving 14.40 g of LiCl (42.39 g/mol) in water to make 0.104 L of solution with a density of 1.102 g/mL?

A physiological saline solution is 0.92% NaCl by mass. What is the osmotic pressure of such a solution at a body temperature of 37°C?

The freezing point of a 0.0925 m solution of ammonium chloride was found to be -0.325°C. What is the actual van't Hoff factor for this salt at this concentration compared to the ideal one of 2? K_f(water) = 1.86°C/m

A 300-mg sample of caffeine was dissolved in 10.0 g of camphor (K_f = 39.7°C/m), decreasing the freezing point of camphor by 3.07°C. What is the molar mass of caffeine?

Identify the following statement as true or false and choose the correct explanation. "For solutions with the same molarity at the same temperature, the pressure needed for reverse osmosis of a sodium chloride solution will always be less than the pressure needed for a calcium chloride solution."

A solution is prepared by adding 1.50 mol glucose, which is not volatile, to 3.50 mol water. What is the vapor pressure of this solution at 25°C given that the vapor pressure of pure water is 23.8 torr?

Which statement regarding osmotic pressure is not correct? Osmotic pressure __________

A solution is made by dissolving 100 g of essentially nonvolatile ethylene glycol (C₂H₆O₂) in 500 g of water. What is the resulting freezing point of the solution (K_f = 1.86°C/m)?

Matter, Energy, and the Origins of the Universe

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Solution Chemistry and the Hydrosphere

Thermochemistry

Properties of Gases: the Air We Breathe

Electrons in Atoms and Periodic Properties

Chemical Bonding and Climate Change

Molecular Geometry and Bonding Theories

Forces Between Ions and Molecules

The Chemistry of Solids

Organic Chemistry: Fuels, Pharmaceuticals, and Materials

Thermodynamics: Spontaneous Processes, Entropy, and Free Energy

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Exam 11: Solutions and Their Colligative Properties

Which statement regarding the fractional distillation of two substances is not correct?

Describe how the data obtained by a measurement of osmotic pressure can be used to determine the molar mass of a compound.

Calculate the minimum pressure that must be applied to achieve reverse osmosis of 0.504 M NaCl at 22C.

What physical property is used to separate the hydrocarbon components in petroleum (crude oil)?

A solution is prepared by adding 0.300 mol glucose, which is not volatile, to 4.50 mol water. What is the vapor pressure of this solution at 25°C given that the vapor pressure of pure water is 23.8 torr?

Isopropyl alcohol has a boiling point of 82.3°C. Solutions of isopropyl alcohol in water have normal boiling points less than 100°C. Is this observation consistent with the following equation? Explain. Tb = iKbm

A solution of 5.00 g of sodium chloride in 1.00 kg of water has a freezing point of -0.299°C. What is the actual van't Hoff factor for this salt at this concentration compared to the ideal one of 2? Kf(water) = 1.86°C/m

What is the molality of a solution produced by dissolving 14.40 g of LiCl (42.39 g/mol) in water to make 0.104 L of solution with a density of 1.102 g/mL?

A physiological saline solution is 0.92% NaCl by mass. What is the osmotic pressure of such a solution at a body temperature of 37°C?

The freezing point of a 0.0925 m solution of ammonium chloride was found to be -0.325°C. What is the actual van't Hoff factor for this salt at this concentration compared to the ideal one of 2? Kf(water) = 1.86°C/m

A 300-mg sample of caffeine was dissolved in 10.0 g of camphor (Kf = 39.7°C/m), decreasing the freezing point of camphor by 3.07°C. What is the molar mass of caffeine?

Identify the following statement as true or false and choose the correct explanation. "For solutions with the same molarity at the same temperature, the pressure needed for reverse osmosis of a sodium chloride solution will always be less than the pressure needed for a calcium chloride solution."

A solution is prepared by adding 1.50 mol glucose, which is not volatile, to 3.50 mol water. What is the vapor pressure of this solution at 25°C given that the vapor pressure of pure water is 23.8 torr?

Which statement regarding osmotic pressure is not correct? Osmotic pressure __________

A solution is made by dissolving 100 g of essentially nonvolatile ethylene glycol (C2H6O2) in 500 g of water. What is the resulting freezing point of the solution (Kf = 1.86°C/m)?

Matter, Energy, and the Origins of the Universe

Atoms, Ions, and Compounds

Chemical Reactions and Earths Composition

Solution Chemistry and the Hydrosphere

Thermochemistry

Properties of Gases: the Air We Breathe

Electrons in Atoms and Periodic Properties

Chemical Bonding and Climate Change

Molecular Geometry and Bonding Theories

Forces Between Ions and Molecules

The Chemistry of Solids

Organic Chemistry: Fuels, Pharmaceuticals, and Materials

Thermodynamics: Spontaneous Processes, Entropy, and Free Energy

Chemical Kinetics

Chemical Equilibrium

Equilibrium in the Aqueous Phase

The Colorful Chemistry of Metals

Electrochemistry and the Quest for Clean Energy

Biochemistry: the Compounds of Life

Nuclear Chemistry

Life and the Periodic Table

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Isopropyl alcohol has a boiling point of 82.3°C. Solutions of isopropyl alcohol in water have normal boiling points less than 100°C. Is this observation consistent with the following equation? Explain. T_b = iK_bm

A solution of 5.00 g of sodium chloride in 1.00 kg of water has a freezing point of -0.299°C. What is the actual van't Hoff factor for this salt at this concentration compared to the ideal one of 2? K_f(water) = 1.86°C/m

The freezing point of a 0.0925 m solution of ammonium chloride was found to be -0.325°C. What is the actual van't Hoff factor for this salt at this concentration compared to the ideal one of 2? K_f(water) = 1.86°C/m

A 300-mg sample of caffeine was dissolved in 10.0 g of camphor (K_f = 39.7°C/m), decreasing the freezing point of camphor by 3.07°C. What is the molar mass of caffeine?

A solution is made by dissolving 100 g of essentially nonvolatile ethylene glycol (C₂H₆O₂) in 500 g of water. What is the resulting freezing point of the solution (K_f = 1.86°C/m)?