Question 1

Predict the freezing point of a solution prepared by dissolving 8.9 g MgCl2 in 98 g H2O. Kf for water is 1.86°C m-1.

Accepted Answer

A)  3.5 °C 
B)  -3.5 °C 
C)  5.3 °C 
D)  -5.3 °C 
E)  -0.51 °C 
A)  3.5 °C 
B)  -3.5 °C 
C)  5.3 °C 
D)  -5.3 °C 
E)  -0.51 °C

Question 2

Gas solubility always increases with temperature.

Accepted Answer

A) True 
 B)False

Question 3

Which of the following statements about ideal solutions is(are) true? I) Entropy effects are important for the formation of ideal solutions.
II) The heat of solution is zero.
III) The vapor pressure varies linearly with the composition.
IV) The forces between like kinds of molecules are (almost) equal to the forces between unlike kinds of molecules.

Accepted Answer

A)  I), II), IV) 
B)  I), III), IV) 
C)  II), III), IV) 
D)  I), II), III) 
E)  I), II), III), IV) 
A)  I), II), IV) 
B)  I), III), IV) 
C)  II), III), IV) 
D)  I), II), III) 
E)  I), II), III), IV)

Question 4

In the solution, a solute is present in the greatest quantity.

Accepted Answer

A) True 
 B)False

Question 5

A saturated solution of ammonium sulfate, (NH4)2SO4, in water at 30°C contains 78.0 g (NH4)2SO4 per 100.0 g H2O. What is the molality of this solution?

Accepted Answer

A)  0.780 m 
B)  1.69 m 
C)  0.590 m 
D)  0.0590 m 
E)  5.90 m 
A)  0.780 m 
B)  1.69 m 
C)  0.590 m 
D)  0.0590 m 
E)  5.90 m

Question 6

The freezing point of pure benzene was measured as 5.49°C. With the same benzene and same equipment, the freezing point of a solution containing 6.582 g of an unknown molecular compound (sold in the store as "moth crystals") in 100.203 grams of benzene was found to be 3.48°C. The cryoscopic constant, Kf, for benzene is 5.12 deg-kg/mole. Calculate the mole weight of the unknown.

Accepted Answer

A)  37.5 g/mol 
B)  16.7 g/mol 
C)  96.6 g/mol 
D)  70.4 g/mol 
E)  167 g/mol 
A)  37.5 g/mol 
B)  16.7 g/mol 
C)  96.6 g/mol 
D)  70.4 g/mol 
E)  167 g/mol

Question 7

A solution that can dissolve no more solute is called:

Accepted Answer

A)  unsaturated 
B)  saturated 
C)  concentrated 
D)  supersaturated 
E)  oversaturated 
A)  unsaturated 
B)  saturated 
C)  concentrated 
D)  supersaturated 
E)  oversaturated

Question 8

Which compound is most likely to be soluble in hexane?

Accepted Answer

A)  water 
B)  acetone (CH3COCH3) 
C)  benzene (C6H12) 
D)  ethyl alcohol (CH3CH2OH) 
E)  chloroform (CHCl3) 
A)  water 
B)  acetone (CH3COCH3) 
C)  benzene (C6H12) 
D)  ethyl alcohol (CH3CH2OH) 
E)  chloroform (CHCl3)

Question 9

If a solution containing 4 mols of A and 6 mols of B boils at 85°C and 1 atm of pressure, and the vapor pressure of pure A at 85°C is 500 mmHg, what is the vapor pressure of pure B at this temperature?

Accepted Answer

A)  933 mmHg 
B)  336 mmHg 
C)  260 mmHg 
D)  576 mmHg 
E)  960 mmHg 
A)  933 mmHg 
B)  336 mmHg 
C)  260 mmHg 
D)  576 mmHg 
E)  960 mmHg

Question 10

3.2 grams of a compound with a mole weight of 96 g/mol dissolved in 50 grams of water gave a solution that freezes at -1.50°C. Kf for water is 1.86°C/molal. The van't Hoff i factor for this solution is ________.

Accepted Answer

A)  0.83 
B)  1.2 
C)  0.21 
D)  0.17 
E)  2.0 
A)  0.83 
B)  1.2 
C)  0.21 
D)  0.17 
E)  2.0

Question 11

Choose the correct statement.

Accepted Answer

A)  Colloids are homogeneous solutions. 
B)  A true colloidal particle will not settle out of the dispersing membrane. 
C)  Colloidal particles can usually pass through a semipermeable membrane. 
D)  Electrolytes are protective colloids. 
E)  Dispersion is the method of preparing colloids from ions or molecules. 
A)  Colloids are homogeneous solutions. 
B)  A true colloidal particle will not settle out of the dispersing membrane. 
C)  Colloidal particles can usually pass through a semipermeable membrane. 
D)  Electrolytes are protective colloids. 
E)  Dispersion is the method of preparing colloids from ions or molecules.

Question 12

Which of the following pairs are more likely to form a solution?

Accepted Answer

A)  chloroform (CHCl3) and acetone (CH3COCH3) 
B)  water and octane (C8H18) 
C)  methanol (CH3OH) and hexane (C6H14) 
D)  water and octyl alcohol (C8H17OH) 
E)  acetone (CH3COCH3) and octane (C8H13) 
A)  chloroform (CHCl3) and acetone (CH3COCH3) 
B)  water and octane (C8H18) 
C)  methanol (CH3OH) and hexane (C6H14) 
D)  water and octyl alcohol (C8H17OH) 
E)  acetone (CH3COCH3) and octane (C8H13)

Question 13

What is the molarity of a saturated solution of potassium sulfate if the solubility is 13 g per 100 g H2O at 25°C? The density of the solution is 1.1 g/mL

Accepted Answer

A)  0.14 M 
B)  1.1 M 
C)  0.96 M 
D)  0.73 M 
E)  0.79 M 
A)  0.14 M 
B)  1.1 M 
C)  0.96 M 
D)  0.73 M 
E)  0.79 M

Question 14

Moles of solute per mole of solution is a definition of ________.

Accepted Answer

A)  molarity 
B)  mole fraction 
C)  percent by weight 
D)  molality 
E)  normality 
A)  molarity 
B)  mole fraction 
C)  percent by weight 
D)  molality 
E)  normality

Question 15

0.25 mol of a nonvolatile, nonionic solute dissolved in 300 g of water (Kf = 1.86) will lower the freezing point how many degrees?

Accepted Answer

A)  0.65 °C 
B)  2.2 °C 
C)  0.14 °C 
D)  1.6 °C 
E)  3.2 °C 
A)  0.65 °C 
B)  2.2 °C 
C)  0.14 °C 
D)  1.6 °C 
E)  3.2 °C

Question 16

Colligative properties are similar in that they all:

Accepted Answer

A)  are due to solvent chemical interactions 
B)  depend on the number of solute particles in solution 
C)  depend on the solvent 
D)  have no effect on the properties of solution 
E)  describe colloids 
A)  are due to solvent chemical interactions 
B)  depend on the number of solute particles in solution 
C)  depend on the solvent 
D)  have no effect on the properties of solution 
E)  describe colloids

Question 17

A magnesium sulfate heptahydrate solution, which is 18.00% by weight in the anhydrous compound, has a density at 20°C of 1.20 g/mL. What is the molality of the anhydrous compound in the solution? (Atomic weights: H = 1.0, O = 16.0, S = 32.1, Mg = 24.3)

Accepted Answer

A)  5.54 M 
B)  1.79 M 
C)  1.82 M 
D)  1.25 M 
E)  1.49 M 
A)  5.54 M 
B)  1.79 M 
C)  1.82 M 
D)  1.25 M 
E)  1.49 M

Question 18

A saline solution begins to freeze at -1.13°C. Express the concentration of NaCl in this solution in mass %. Kf for water is 1.86°C m-1.

Accepted Answer

A)  3.48% 
B)  1.74% 
C)  0.870% 
D)  17.8% 
E)  8.90% 
A)  3.48% 
B)  1.74% 
C)  0.870% 
D)  17.8% 
E)  8.90%

Question 19

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 nitrogen in water under an atmospheric pressure of 760 mmHg, assuming that air is 80% N2 and 20% O2.

Accepted Answer

A)  6.23 × 10-4 m 
B)  7.79 × 10-4 m 
C)  4.99 × 10-4 m 
D)  1.25 × 10-4 m 
E)  6.16 × 10-3 m 
A)  6.23 × 10-4 m 
B)  7.79 × 10-4 m 
C)  4.99 × 10-4 m 
D)  1.25 × 10-4 m 
E)  6.16 × 10-3 m

Question 20

A sweetened cup of coffee is an example of a:

Accepted Answer

A)  heterogeneous mixture 
B)  homogeneous mixture 
C)  solid solution 
D)  pure liquid 
E)  gaseous solute in a liquid solvent 
A)  heterogeneous mixture 
B)  homogeneous mixture 
C)  solid solution 
D)  pure liquid 
E)  gaseous solute in a liquid solvent

Exam 13: Solutions and Their Physical Properties

Predict the freezing point of a solution prepared by dissolving 8.9 g MgCl2 in 98 g H2O. Kf for water is 1.86°C m-1.

Gas solubility always increases with temperature.

In the solution, a solute is present in the greatest quantity.

A saturated solution of ammonium sulfate, (NH4)2SO4, in water at 30°C contains 78.0 g (NH4)2SO4 per 100.0 g H2O. What is the molality of this solution?

A solution that can dissolve no more solute is called:

Which compound is most likely to be soluble in hexane?

If a solution containing 4 mols of A and 6 mols of B boils at 85°C and 1 atm of pressure, and the vapor pressure of pure A at 85°C is 500 mmHg, what is the vapor pressure of pure B at this temperature?

3.2 grams of a compound with a mole weight of 96 g/mol dissolved in 50 grams of water gave a solution that freezes at -1.50°C. Kf for water is 1.86°C/molal. The van't Hoff i factor for this solution is ________.

Choose the correct statement.

Which of the following pairs are more likely to form a solution?

What is the molarity of a saturated solution of potassium sulfate if the solubility is 13 g per 100 g H2O at 25°C? The density of the solution is 1.1 g/mL

Moles of solute per mole of solution is a definition of ________.

0.25 mol of a nonvolatile, nonionic solute dissolved in 300 g of water (Kf = 1.86) will lower the freezing point how many degrees?

Colligative properties are similar in that they all:

A magnesium sulfate heptahydrate solution, which is 18.00% by weight in the anhydrous compound, has a density at 20°C of 1.20 g/mL. What is the molality of the anhydrous compound in the solution? (Atomic weights: H = 1.0, O = 16.0, S = 32.1, Mg = 24.3)

A saline solution begins to freeze at -1.13°C. Express the concentration of NaCl in this solution in mass %. Kf for water is 1.86°C m-1.

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 nitrogen in water under an atmospheric pressure of 760 mmHg, assuming that air is 80% N2 and 20% O2.

A sweetened cup of coffee is an example of a:

Matter - Its Properties and Measurement

Atoms and the Atomic Theory

Chemical Compounds

Chemical Reactions

Introduction to Reactions in Aqueous Solutions

Gases

Thermochemistry

Electrons in Atoms

The Periodic Table and Some Atomic Properties

Chemical Bonding I: Basic Concepts

Chemical Bonding II: Additional Aspects

Intermolecular Forces: Liquids and Solids

Chemical Kinetics

Principles of Chemical Equilibrium

Acids and Bases

Additional Aspects of Acid-Base Equilibria

Solubility and Complex-Ion Equilibria

Spontaneous Change: Entropy and Free Energy

Electrochemistry

Main Group Elements I: Groups 1, 2, 13, and 14

Main Group Elements II: Groups 18, 17, 16, 15, and Hydrogen

The Transition Elements

Complex Ions and Coordination Compounds

Nuclear Chemistry 1-41

Structures of Organic Compounds

Reactions of Organic Compounds

Chemistry of the Living State

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Predict the freezing point of a solution prepared by dissolving 8.9 g MgCl₂ in 98 g H₂O. Kf for water is 1.86°C m-1.

A saturated solution of ammonium sulfate, (NH₄)₂SO₄, in water at 30°C contains 78.0 g (NH₄)₂SO₄per 100.0 g H₂O. What is the molality of this solution?

What is the molarity of a saturated solution of potassium sulfate if the solubility is 13 g per 100 g H₂O at 25°C? The density of the solution is 1.1 g/mL

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 nitrogen in water under an atmospheric pressure of 760 mmHg, assuming that air is 80% N₂ and 20% O₂.