Question 1

Solutions are made that contain 0.1 moles of each of the following compounds below in 100 g of H2O. Choose the compound whose solution will have the lowest freezing point.

Accepted Answer

A)   MgCl2
B)   KClO3
C)   CO2
D)   MgSO4
E)   NaBr A

Question 2

Liquid Q is a polar solvent and liquid R is a nonpolar solvent. On the basis of this information, you would expect:

Accepted Answer

A)   both liquids to be miscible with a third liquid T
B)   liquid Q to be miscible with liquid R
C)   NaCl to be soluble to both Q and R
D)   liquid Q and H2O to be miscible
E)   liquid R and H2O to be miscible D

Question 3

What is the correct value for the weight of Na3PO4 needed to make 100 mL of a 0.50 molar solution?

Accepted Answer

A)   16.4 g
B)   8.2 g
C)   0.05 g
D)   82 g
E)   4.1 g B

Question 4

Which definition is INCORRECT?

Accepted Answer

A)   mole fraction = moles of solute/moles of solution
B)   molality = moles of solute/kilogram of solvent
C)   weight percent = grams of solute/100 grams of solution
D)   molarity = moles of solute/liter of solution
E)   volume percent=volume of solute/volume of solution

Question 5

The stronger the forces between solute and solvent molecules, the more exothermic the solution process.

Accepted Answer

A) True 
 B)False

Question 6

Molality is independent of temperature, molarity is dependent on temperature.

Accepted Answer

A) True 
 B)False

Question 7

The vapor pressures of pure hexane and pure heptane at 25°C are 151.4 mmHg and 45.62 mmHg respectively. A solution contains 0.800 mol fraction n-hexane and 0.200 mol fraction n-heptane. What is the composition of the vapor in equilibrium with this solution at 25°C?

Accepted Answer

A)   80.0% hexane, 20.0% heptane
B)   50.0% hexane, 50.0% heptane
C)   77.0% hexane, 23.0% heptane
D)   45.0% hexane, 55.0% heptane
E)   93.0% hexane, 7.0% heptane

Question 8

252 mL of 3.00 M H2SO4 are added to 1.50 L of 0.500 M H2SO4. What is the concentration of the resulting solution?

Accepted Answer

A)   1.50 M
B)   0.860 M
C)   2.64 M
D)   1.75 M
E)   1.25 M

Question 9

Exactly 375.0 mg of an unknown protein is dissolved in enough water to give 50.00 mL of solution and the osmotic pressure determined as 3.25 mmHg at 298 K. Estimate the molar mass of this protein.

Accepted Answer

A)   42,900 g/mol
B)   3,600 g/mol
C)   56,400 g/mol
D)   139,000 g/mol

Question 10

0.0800 g of a compound with the empirical formula C2H2N is dissolved in 10.00 g benzene. The resulting solution freezes at 4.99°C. Benzene freezes at 5.48°C and has a freezing point depression constant of Kf = 4.90°C/m. What is the molecular formula of the compound?

Accepted Answer

A)   C3H2N
B)   C3H3N
C)   C4H4N2
D)   C6H6N3
E)   C8H8N4

Question 11

Which of the following organic substances is most readily soluble in water?

Accepted Answer

A)   benzene
B)   pyridine
C)   octane
D)   carbon tetrachloride
E)   toluene

Question 12

Henry's Law states that:

Accepted Answer

A)   a supersaturated solution is unstable
B)   the solubility of a gas increases as the gas pressure is increased
C)   the solubility of a gas decreases as the gas pressure is increased
D)   a concentrated solution lowers the freezing point of a solution
E)   a concentrated solution increases the boiling point of a solution

Question 13

An isotonic solution will produce an osmotic pressure of 7.84 atm measured against pure water at human body temperature (37.0°C). How many grams of sodium chloride must be dissolved in a liter of water to produce an isotonic solution?

Accepted Answer

A)   75.5 g
B)   151 g
C)   2.58 g
D)   9.00 g
E)   18.0 g

Question 14

A solution is called "ideal" when:

Accepted Answer

A)   all intermolecular forces of attraction are the same, resulting in no net enthalpy change when the solution is formed from its components.
B)   the forces of attraction between solute molecules exceed those between solute and solvent molecules.
C)   the forces of attraction between solute and solvent molecules are somewhat smaller than between solute-solute molecules or solvent-solvent molecules.
D)   the forces of attraction between solvent molecules exceed those between solute and solvent molecules.
E)   the forces of attraction between solute molecules and solvent molecules are much smaller than between solute-solute molecules or solvent-solvent molecules.

Question 15

Henry's Law constants for aqueous solutions at 25°C are 8.20 × 10-7 molal/mmHg for N2 and 1.62 × 10-6 molal/mmHg for O2. Determine the solubility of oxygen in water under an atmospheric pressure of 760 mmHg, assuming that air is 80% N2 and 20% O2.

Accepted Answer

A)   6.2 × 10-3 m
B)   2.5 × 10-4 m
C)   1.3 × 10-4 m
D)   5.0 × 10-4 m
E)   1.2 × 10-3 m

Question 16

A solution containing 3.24 g of sulfur in 40 g of benzene boils 0.81°C above the boiling point of pure benzene. Determine the number of S atoms in one molecule of dissolved sulfur. Kb for benzene is 2.53°C m-1.

Accepted Answer

A)   10
B)   12
C)   6
D)   8
E)   4

Question 17

Determine the osmotic pressure at 25 °C of an aqueous solution that is 0.028 M NaNO3.

Accepted Answer

A)   1.37 atm
B)   0.685 atm
C)   0.0729 atm
D)   0.0364 atm
E)   2.06 atm

Question 18

A solution composed of 5 moles of acetone (CH3COCH3, P°A = 324 mmHg) and 5 moles of chloroform (CHCl3, P°C = 274 mmHg) has a vapor pressure of 236 mmHg. Which one of the following statements is completely true about this solution?

Accepted Answer

A)   The solution shows a negative deviation from Raoult's law and thus possesses a maximum boiling azeotrope.
B)   The solution process is exothermic because the forces between unlike molecules are weaker than those between like molecules.
C)   The solution shows a positive deviation from Raoult's law.
D)   The solution possesses a minimum boiling azeotrope because it shows a negative deviation from Raoult's law.
E)   The solution obeys Raoult's Law.

Question 19

What is the osmotic pressure in mmHg of 6.00 L of a 0.108 M solution at 30°C if three moles of ions are produced in aqueous solution for every mole of solute dissolved?

Accepted Answer

A)   8.05 mmHg
B)   3.68 × 104 mmHg
C)   2.04 × 103 mmHg
D)   0.0613 mmHg
E)   6.13 × 103 mmHg

Question 20

Which compound is most likely to be soluble in water?

Accepted Answer

A)   butyl alcohol (CH3CH2CH2CH2OH) 
B)   ethylene glycol (HOCH2CH2OH) 
C)   hexane (C6H14) 
D)   benzene (C6H12) 
E)   iodine (I2)

Exam 13: Solutions and Their Physical Properties

Solutions are made that contain 0.1 moles of each of the following compounds below in 100 g of H₂O. Choose the compound whose solution will have the lowest freezing point.

Liquid Q is a polar solvent and liquid R is a nonpolar solvent. On the basis of this information, you would expect:

What is the correct value for the weight of Na₃PO₄needed to make 100 mL of a 0.50 molar solution?

Which definition is INCORRECT?

The stronger the forces between solute and solvent molecules, the more exothermic the solution process.

Molality is independent of temperature, molarity is dependent on temperature.

The vapor pressures of pure hexane and pure heptane at 25°C are 151.4 mmHg and 45.62 mmHg respectively. A solution contains 0.800 mol fraction n-hexane and 0.200 mol fraction n-heptane. What is the composition of the vapor in equilibrium with this solution at 25°C?

252 mL of 3.00 M H₂SO₄are added to 1.50 L of 0.500 M H₂SO₄. What is the concentration of the resulting solution?

Exactly 375.0 mg of an unknown protein is dissolved in enough water to give 50.00 mL of solution and the osmotic pressure determined as 3.25 mmHg at 298 K. Estimate the molar mass of this protein.

0.0800 g of a compound with the empirical formula C₂H₂N is dissolved in 10.00 g benzene. The resulting solution freezes at 4.99°C. Benzene freezes at 5.48°C and has a freezing point depression constant of Kf = 4.90°C/m. What is the molecular formula of the compound?

Which of the following organic substances is most readily soluble in water?

Henry's Law states that:

An isotonic solution will produce an osmotic pressure of 7.84 atm measured against pure water at human body temperature (37.0°C) . How many grams of sodium chloride must be dissolved in a liter of water to produce an isotonic solution?

A solution is called "ideal" when:

Henry's Law constants for aqueous solutions at 25°C are 8.20 × 10^-7 molal/mmHg for N₂ and 1.62 × 10^-6 molal/mmHg for O₂. Determine the solubility of oxygen in water under an atmospheric pressure of 760 mmHg, assuming that air is 80% N₂ and 20% O₂.

A solution containing 3.24 g of sulfur in 40 g of benzene boils 0.81°C above the boiling point of pure benzene. Determine the number of S atoms in one molecule of dissolved sulfur. Kb for benzene is 2.53°C m-1.

Determine the osmotic pressure at 25 °C of an aqueous solution that is 0.028 M NaNO₃.

A solution composed of 5 moles of acetone (CH₃COCH₃, P°A = 324 mmHg) and 5 moles of chloroform (CHCl₃, P°C = 274 mmHg) has a vapor pressure of 236 mmHg. Which one of the following statements is completely true about this solution?

What is the osmotic pressure in mmHg of 6.00 L of a 0.108 M solution at 30°C if three moles of ions are produced in aqueous solution for every mole of solute dissolved?

Which compound is most likely to be soluble in water?