Question 1

A salt solution sits in an open beaker.Assuming constant temperature and pressure,the vapor pressure of the solution

Accepted Answer

A) increases over time 
B) decreases over time 
C) stays the same over time 
D) need to know which salt is in the solution to answer this 
E) need to know the temperature and pressure to answer this

Question 2

Diagram and label a vapor pressure diagram for an ideal solution of two volatile liquids.Indicate the deviation predicted by an endothermic heat of solution.

Accepted Answer

The answer of Diagram and label a vapor pressure diagram...

Question 3

What partial pressure of nitrogen gas is required in order for 0.00134 g of the gas to dissolve in 13.1 mL of pure water? The Henry's law constant for nitrogen gas is 6.1 $\times$ 10-4 M atm-1.

Accepted Answer

A) 6.2 $\times$ 10-8 atm 
B) 1.7 $\times$ 10-1 atm 
C) 6.0 $\times$ 100 atm 
D) 2.9 $\times$ 10-8 atm 
E) 1.7 $\times$ 10-2 atm

Question 4

When 0.811 g of NH4NO3 was added to 150.0 g of water in a Styrofoam cup,the temperature dropped by 0.413°C.The heat capacity of H2O is 4.18 J/g°C.Assume the specific heat of the solution equals that of pure H2O and that the calorimeter neither absorbs nor leaks heat.The molar heat of solution of solid NH4NO3 is:

Accepted Answer

A) +257 J/mol 
B) +25.7 kJ/mol 
C) +2.57 kJ/mol 
D) -2.57 kJ/mol 
E) -257 J/mol

Question 5

What is the percent by mass of ethanol (C₂H₅OH)in a 1.5-m aqueous solution?

Accepted Answer

The answer of What is the percent by mass of...

Question 6

Which of the following will cause the calculated molar mass of a compound determined by the freezing-point depression method to be greater than the true molar mass?

Accepted Answer

A) Water gets into the solvent after the freezing point of the pure solvent is determined. 
B) Some of the solute molecules break apart. 
C) The mass of solvent is smaller than determined from the weighing. 
D) While adding the solute,some was spilled on the lab bench. 
E) All of the above.

Question 7

When a 49.1-g sample of an unknown compound is dissolved in 500.g of benzene,the freezing point of the resulting solution is 3.77°C.The freezing point of pure benzene is 5.48°C and Kf for benzene is 5.12°C/m.Calculate the molar mass of the unknown compound.

Accepted Answer

A) 147 g/mol 
B) 28.7 g/mol 
C) 251 g/mol 
D) 588 g/mol 
E) 294 g/mol

Question 8

Consider pure water separated from an aqueous sugar solution by a semipermeable membrane,which allows water to pass freely but not sugar.After some time has passed,the concentration of sugar solution:

Accepted Answer

A) will have increased 
B) will have decreased 
C) will not have changed 
D) might have increased or decreased depending on other factors 
E) will be the same on both sides of the membrane

Question 9

Thyroxine,an important hormone that controls the rate of metabolism in the body,can be isolated from the thyroid gland.If 0.455 g of thyroxine is dissolved in 10.0 g of benzene,the freezing point of the solution could be measured as 5.144°C.Pure benzene freezes at 5.444°C and has a value for the molal freezing point depression constant of Kf of 5.12°C/m.What is the approximate molar mass of thyroxine?

Accepted Answer

A) 7.77 $\times$ 105 g/mol 
B) 777 g/mol 
C) 7.77 g/mol 
D) 11.3 g/mol 
E) 42.8 g/mol

Question 10

A 3.140 molal solution of NaCl is prepared.How many grams of NaCl are present in a sample containing 2.314 kg of water?

Accepted Answer

A) 726.6 g 
B) 124.3 g 
C) 257.6 g 
D) 424.6 g 
E) none of these

Question 11

What type of colloid is formed when a gas is dispersed in a liquid?

Accepted Answer

A) foam 
B) gel 
C) emulsion 
D) sol 
E) aerosol

Question 12

What is the mole percent of ethanol (C2H5OH),which consists of 71.0 g of ethanol for every 16.7 g of water present?

Accepted Answer

A) 62.4% 
B) 1.66% 
C) 9.23% 
D) 81.0% 
E) 37.6%

Question 13

What type of colloid is formed when a liquid is dispersed in a gas?

Accepted Answer

A) foam 
B) aerosol 
C) emulsion 
D) sol 
E) gel

Question 14

At 40°C,heptane has a vapor pressure of about 92.2 torr and octane has a vapor pressure of about 31.2 torr.Assuming ideal behavior,what is the vapor pressure of a solution that contains twice as many moles of heptane as octane?

Accepted Answer

A) 61.5 torr 
B) 51.5 torr 
C) 71.9 torr 
D) 82.3 torr 
E) none of these

Question 15

Rank the following compounds according to increasing solubility in water. I.
CH3-CH2-CH2-CH3
II.
CH3-CH2-O-CH2-CH3
III.
CH3-CH2-OH
IV.
CH3-OH

Accepted Answer

A) I < III < IV < II 
B) I < II < IV < III 
C) III < IV < II < I 
D) I < II < III < IV 
E) None of these (A-
D) is correct.

Question 16

For each of the following solutions,describe the deviation with respect to Raoult's Law.
-hexane (C6H14)and octane (C8H18)

Accepted Answer

A) relatively ideal 
B) positive deviation 
C) negative deviation 
D) more information needed 
E) none of these

Question 17

A solute added to a solvent raises the boiling point of the solution because:

Accepted Answer

A) The temperature to cause boiling must be great enough to boil not only the solvent but also the solute. 
B) The solute particles lower the solvent's vapor pressure,thus requiring a higher temperature to cause boiling. 
C) The solute particles raise the solvent's vapor pressure,thus requiring a higher temperature to cause boiling. 
D) The solute increases the volume of the solution,and an increase in volume requires an increase in the temperature to reach the boiling point (derived from PV = nRT). 
E) Two of the above are correct.

Question 18

Determine the osmotic pressure of a solution that contains 0.048 g of a hydrocarbon solute (molar mass = 340 g/mol)dissolved in benzene to make a 350-mL solution.The temperature is 20.0°C.

Accepted Answer

A) 0.50 torr 
B) 2.5 torr 
C) 3.3 torr 
D) 7.4 torr 
E) 6.9 torr

Question 19

When a substance dissolves in water,heat energy is released if:

Accepted Answer

A) The lattice energy is positive. 
B) The hydration energy is positive. 
C) The hydration energy is more negative than the lattice energy is positive. 
D) The hydration energy is negative. 
E) None of these (A-
D) .

Question 20

Calculate the molality of C2H5OH in a water solution that is prepared by mixing 50.0 mL of C2H5OH with 112.7 mL of H2O at 20°C.The density of the C2H5OH is 0.789 g/mL at 20°C.(Assume the density of water at this temperature is 1.00 g/mL. )

Accepted Answer

A) 0.00963 m 
B) 0.155 m 
C) 0.132 m 
D) 7.60 m 
E) 9.63 m

Exam 11: Properties of Solutions

A salt solution sits in an open beaker.Assuming constant temperature and pressure,the vapor pressure of the solution

Diagram and label a vapor pressure diagram for an ideal solution of two volatile liquids.Indicate the deviation predicted by an endothermic heat of solution.

What partial pressure of nitrogen gas is required in order for 0.00134 g of the gas to dissolve in 13.1 mL of pure water? The Henry's law constant for nitrogen gas is 6.1 $\times$ 10^-⁴ M atm^-¹.

What is the percent by mass of ethanol (C₂H₅OH)in a 1.5-m aqueous solution?

Which of the following will cause the calculated molar mass of a compound determined by the freezing-point depression method to be greater than the true molar mass?

When a 49.1-g sample of an unknown compound is dissolved in 500.g of benzene,the freezing point of the resulting solution is 3.77°C.The freezing point of pure benzene is 5.48°C and K_f for benzene is 5.12°C/m.Calculate the molar mass of the unknown compound.

Consider pure water separated from an aqueous sugar solution by a semipermeable membrane,which allows water to pass freely but not sugar.After some time has passed,the concentration of sugar solution:

A 3.140 molal solution of NaCl is prepared.How many grams of NaCl are present in a sample containing 2.314 kg of water?

What type of colloid is formed when a gas is dispersed in a liquid?

What is the mole percent of ethanol (C₂H₅OH) ,which consists of 71.0 g of ethanol for every 16.7 g of water present?

What type of colloid is formed when a liquid is dispersed in a gas?

At 40°C,heptane has a vapor pressure of about 92.2 torr and octane has a vapor pressure of about 31.2 torr.Assuming ideal behavior,what is the vapor pressure of a solution that contains twice as many moles of heptane as octane?

Rank the following compounds according to increasing solubility in water. I. CH₃-CH₂-CH₂-CH₃ II. CH₃-CH₂-O-CH₂-CH₃ III. CH₃-CH₂-OH IV. CH₃-OH

For each of the following solutions,describe the deviation with respect to Raoult's Law. -hexane (C₆H₁₄) and octane (C₈H₁₈)

A solute added to a solvent raises the boiling point of the solution because:

Determine the osmotic pressure of a solution that contains 0.048 g of a hydrocarbon solute (molar mass = 340 g/mol) dissolved in benzene to make a 350-mL solution.The temperature is 20.0°C.

When a substance dissolves in water,heat energy is released if:

Calculate the molality of C₂H₅OH in a water solution that is prepared by mixing 50.0 mL of C₂H₅OH with 112.7 mL of H₂O at 20°C.The density of the C₂H₅OH is 0.789 g/mL at 20°C.(Assume the density of water at this temperature is 1.00 g/mL. )

Exam 11: Properties of Solutions

A salt solution sits in an open beaker.Assuming constant temperature and pressure,the vapor pressure of the solution

Diagram and label a vapor pressure diagram for an ideal solution of two volatile liquids.Indicate the deviation predicted by an endothermic heat of solution.

What partial pressure of nitrogen gas is required in order for 0.00134 g of the gas to dissolve in 13.1 mL of pure water? The Henry's law constant for nitrogen gas is 6.1 ×\times× 10-4 M atm-1.

What is the percent by mass of ethanol (C2H5OH)in a 1.5-m aqueous solution?

Which of the following will cause the calculated molar mass of a compound determined by the freezing-point depression method to be greater than the true molar mass?

When a 49.1-g sample of an unknown compound is dissolved in 500.g of benzene,the freezing point of the resulting solution is 3.77°C.The freezing point of pure benzene is 5.48°C and Kf for benzene is 5.12°C/m.Calculate the molar mass of the unknown compound.

Consider pure water separated from an aqueous sugar solution by a semipermeable membrane,which allows water to pass freely but not sugar.After some time has passed,the concentration of sugar solution:

A 3.140 molal solution of NaCl is prepared.How many grams of NaCl are present in a sample containing 2.314 kg of water?

What type of colloid is formed when a gas is dispersed in a liquid?

What is the mole percent of ethanol (C2H5OH) ,which consists of 71.0 g of ethanol for every 16.7 g of water present?

What type of colloid is formed when a liquid is dispersed in a gas?

At 40°C,heptane has a vapor pressure of about 92.2 torr and octane has a vapor pressure of about 31.2 torr.Assuming ideal behavior,what is the vapor pressure of a solution that contains twice as many moles of heptane as octane?

Rank the following compounds according to increasing solubility in water. I. CH3-CH2-CH2-CH3 II. CH3-CH2-O-CH2-CH3 III. CH3-CH2-OH IV. CH3-OH

For each of the following solutions,describe the deviation with respect to Raoult's Law. -hexane (C6H14) and octane (C8H18)

A solute added to a solvent raises the boiling point of the solution because:

Determine the osmotic pressure of a solution that contains 0.048 g of a hydrocarbon solute (molar mass = 340 g/mol) dissolved in benzene to make a 350-mL solution.The temperature is 20.0°C.

When a substance dissolves in water,heat energy is released if:

Calculate the molality of C2H5OH in a water solution that is prepared by mixing 50.0 mL of C2H5OH with 112.7 mL of H2O at 20°C.The density of the C2H5OH is 0.789 g/mL at 20°C.(Assume the density of water at this temperature is 1.00 g/mL. )

What partial pressure of nitrogen gas is required in order for 0.00134 g of the gas to dissolve in 13.1 mL of pure water? The Henry's law constant for nitrogen gas is 6.1 $\times$ 10^-⁴ M atm^-¹.

What is the percent by mass of ethanol (C₂H₅OH)in a 1.5-m aqueous solution?

When a 49.1-g sample of an unknown compound is dissolved in 500.g of benzene,the freezing point of the resulting solution is 3.77°C.The freezing point of pure benzene is 5.48°C and K_f for benzene is 5.12°C/m.Calculate the molar mass of the unknown compound.

What is the mole percent of ethanol (C₂H₅OH) ,which consists of 71.0 g of ethanol for every 16.7 g of water present?

Rank the following compounds according to increasing solubility in water. I. CH₃-CH₂-CH₂-CH₃ II. CH₃-CH₂-O-CH₂-CH₃ III. CH₃-CH₂-OH IV. CH₃-OH

For each of the following solutions,describe the deviation with respect to Raoult's Law. -hexane (C₆H₁₄) and octane (C₈H₁₈)

Calculate the molality of C₂H₅OH in a water solution that is prepared by mixing 50.0 mL of C₂H₅OH with 112.7 mL of H₂O at 20°C.The density of the C₂H₅OH is 0.789 g/mL at 20°C.(Assume the density of water at this temperature is 1.00 g/mL. )