Question 1

The pK1 of citric acid is 3.09.What is the citric acid : monosodium citrate ratio in a 1.0 M citric acid solution with a pH of 2.09?

Accepted Answer

A) 10:1 
B) 1:1 
C) 1:10 
D) 10:11 
E) 1:11 
A) 10:1 
B) 1:1 
C) 1:10 
D) 10:11 
E) 1:11

Question 2

In the energetics of transferring hydrocarbons from water to nonpolar solvents, the factor T$\Delta$S is commonly

Accepted Answer

A) negative. 
B) positive. 
C) unmeasurable. 
D) unimportant. 
E) assumed to be zero. 
A) negative. 
B) positive. 
C) unmeasurable. 
D) unimportant. 
E) assumed to be zero.

Question 3

The pKs of succinic acid are 4.21 and 5.64.How many grams of monosodium succinate (FW = 140 g/mol)and disodium succinate (FW = 162 g/mol)must be added to 1 L of water to produce a solution with a pH 5.28 and a total solute concentration of 100 mM? (Assume the total volume remains 1 liter, answer in grams monosodium succinate, grams disodium succinate, respectively.)

Accepted Answer

A) 11.3 g, 4.2 g 
B) 9.7 g, 4.9 g 
C) 4.9 g, 9.7 g 
D) 14.9 g, 1.1 g 
E) 1.1 g, 14.9 g 
A) 11.3 g, 4.2 g 
B) 9.7 g, 4.9 g 
C) 4.9 g, 9.7 g 
D) 14.9 g, 1.1 g 
E) 1.1 g, 14.9 g

Question 4

Kw, the ionization constant of water, is _____ at _____.

Accepted Answer

A) 10-7; 25°C 
B) 107; 25K 
C) 1014; 25°C 
D) 10-14; 25°C 
E) 10-14; 0°C 
A) 10-7; 25°C 
B) 107; 25K 
C) 1014; 25°C 
D) 10-14; 25°C 
E) 10-14; 0°C

Question 5

Weak acids

Accepted Answer

A) are only partially ionized in an aqueous solution. 
B) give solutions with a high pH. 
C) do not provide hydronium ions. 
D) are almost insoluble in water. 
E) are of no value in a buffering system. 
A) are only partially ionized in an aqueous solution. 
B) give solutions with a high pH. 
C) do not provide hydronium ions. 
D) are almost insoluble in water. 
E) are of no value in a buffering system.

Question 6

Matching
-For the ______ represented by D-H...A, the donor D is weakly acidic and the acceptor A is weakly basic.

Accepted Answer

A) hydrogen bond 
B) rotational 
C) H₃PO₄ 
D) H₂PO₄– 
E) HPO₄ 2–
F)disordered
G)positive entropy
H)negative entropy
I)higher electronegativity
J)insoluble
K)tetrahedral arrangement
L)acid
M)base
N)only partially ionized 
A) hydrogen bond 
B) rotational 
C) H₃PO₄ 
D) H₂PO₄– 
E) HPO₄ 2–
F)disordered
G)positive entropy
H)negative entropy
I)higher electronegativity
J)insoluble
K)tetrahedral arrangement
L)acid
M)base
N)only partially ionized

Question 7

To make a phosphate buffer at pH 6.82 starting with one liter of 10 mM phosphoric acid (pKs are 2.15, 6.82, and 12.38), you could add

Accepted Answer

A) 5 millimoles of HCl. 
B) 20 millimoles of K+. 
C) 25 millimoles of HCl. 
D) 15 millimoles of KOH. 
E) You can't make a buffer by adding HCl or KOH. 
A) 5 millimoles of HCl. 
B) 20 millimoles of K+. 
C) 25 millimoles of HCl. 
D) 15 millimoles of KOH. 
E) You can't make a buffer by adding HCl or KOH.

Question 8

Amphiphilic molecules

Accepted Answer

A) have both oxidizing and reducing groups. 
B) are micelles. 
C) have chromophores in two different wavelength regions. 
D) have both acidic and basic groups. 
E) have both hydrophilic and hydrophobic groups. 
A) have both oxidizing and reducing groups. 
B) are micelles. 
C) have chromophores in two different wavelength regions. 
D) have both acidic and basic groups. 
E) have both hydrophilic and hydrophobic groups.

Question 9

Osmotic pressure is a function of

Accepted Answer

A) humidity. 
B) solute size. 
C) solute concentration. 
D) van der Waals forces. 
E) solute vapor pressure. 
A) humidity. 
B) solute size. 
C) solute concentration. 
D) van der Waals forces. 
E) solute vapor pressure.

Question 10

Ice

Accepted Answer

A) is a crystal of water molecules packed in an open structure stabilized by hydrogen bonds. 
B) is less dense than liquid water. 
C) contains 17% more hydrogen bonds then water. 
D) All of the statements above are true. 
E) None of the statements above are true. 
A) is a crystal of water molecules packed in an open structure stabilized by hydrogen bonds. 
B) is less dense than liquid water. 
C) contains 17% more hydrogen bonds then water. 
D) All of the statements above are true. 
E) None of the statements above are true.

Question 11

A buffer contains 0.010 mol of lactic acid (pKa = 3.86)and 0.050 mol sodium lactate per liter of aqueous solution.
a.Calculate the pH of this buffer.
b.Calculate the pH after 5.0 mL of 0.50 M HCl is added to 1 liter of the buffer (assume the total volume will be 1005 mL).

Accepted Answer

a.pH = pK_a + log [A⁻

Question 12

In a hydrogen bond between a water molecule and another biomolecule

Accepted Answer

A) a hydrogen ion on the water molecule forms an ionic bond with a hydride ion on the other molecule. 
B) the partial charge on a hydrogen of the water molecule interacts with the partial charge on a hydrogen of the other molecule. 
C) the hydrogen bond will typically form between a hydrogen atom of the water molecule and either a nitrogen, sulfur, or oxygen atom of the other molecule. 
D) a hydrogen on the water molecule forms a covalent bond with a hydrogen atom on the other molecule. 
E) the hydrogen atom is located between an oxygen atom of the water and a carbon atom of the other molecule. 
A) a hydrogen ion on the water molecule forms an ionic bond with a hydride ion on the other molecule. 
B) the partial charge on a hydrogen of the water molecule interacts with the partial charge on a hydrogen of the other molecule. 
C) the hydrogen bond will typically form between a hydrogen atom of the water molecule and either a nitrogen, sulfur, or oxygen atom of the other molecule. 
D) a hydrogen on the water molecule forms a covalent bond with a hydrogen atom on the other molecule. 
E) the hydrogen atom is located between an oxygen atom of the water and a carbon atom of the other molecule.

Question 13

Hydrophobic interactions between nonpolar molecules

Accepted Answer

A) result from the tendency of water to maximize contact with nonpolar molecules. 
B) are the result of strong attractions between nonpolar molecules. 
C) are the result of strong repulsion between water and nonpolar molecules. 
D) depend on strong permanent dipoles in the nonpolar molecules. 
E) require the presence of surrounding water molecules. 
A) result from the tendency of water to maximize contact with nonpolar molecules. 
B) are the result of strong attractions between nonpolar molecules. 
C) are the result of strong repulsion between water and nonpolar molecules. 
D) depend on strong permanent dipoles in the nonpolar molecules. 
E) require the presence of surrounding water molecules.

Question 14

The pH at the midpoint in the titration of an acid with a base is

Accepted Answer

A) equal to the pK of the corresponding acid. 
B) equal to the pK of the corresponding base. 
C) equal to 14 minus the pK of the corresponding acid. 
D) equal to 14 plus the pK of the corresponding base. 
E) none of the above 
A) equal to the pK of the corresponding acid. 
B) equal to the pK of the corresponding base. 
C) equal to 14 minus the pK of the corresponding acid. 
D) equal to 14 plus the pK of the corresponding base. 
E) none of the above

Question 15

Matching
-The polarity of the O-H bond is caused by the ______ of oxygen relative to that of hydrogen.

Accepted Answer

A) hydrogen bond 
B) rotational 
C) H₃PO₄ 
D) H₂PO₄– 
E) HPO₄ 2–
F)disordered
G)positive entropy
H)negative entropy
I)higher electronegativity
J)insoluble
K)tetrahedral arrangement
L)acid
M)base
N)only partially ionized 
A) hydrogen bond 
B) rotational 
C) H₃PO₄ 
D) H₂PO₄– 
E) HPO₄ 2–
F)disordered
G)positive entropy
H)negative entropy
I)higher electronegativity
J)insoluble
K)tetrahedral arrangement
L)acid
M)base
N)only partially ionized

Question 16

Urea is a water-soluble product of nitrogen metabolism.How many hydrogen bonds can one urea molecule donate to surrounding water molecules?

Accepted Answer

A) 2 
B) 3 
C) 4 
D) 5 
E) 6 
A) 2 
B) 3 
C) 4 
D) 5 
E) 6

Question 17

The strongest noncovalent interactions are

Accepted Answer

A) ionic interactions. 
B) hydrogen bonds. 
C) dipole-dipole interactions. 
D) London dispersion forces. 
E) van der Waals forces. 
A) ionic interactions. 
B) hydrogen bonds. 
C) dipole-dipole interactions. 
D) London dispersion forces. 
E) van der Waals forces.

Question 18

A solution is made by mixing 0.05 mL of 1.0 M HCl with 999.95 mL of pure water.Calculate the pH of the resulting solution (assume the total volume is 1.0 L).

Accepted Answer

A) 2.7 
B) 4.3 
C) 9.7 
D) 7.0 
E) 5.0 
A) 2.7 
B) 4.3 
C) 9.7 
D) 7.0 
E) 5.0

Question 19

What is the approximate pKa of a weak acid HA if a solution 0.1 M HA and 0.3 M A- has a pH of 6.5?

Accepted Answer

A) 5.8 
B) 6.0 
C) 6.2 
D) 6.4 
E) 6.6 
A) 5.8 
B) 6.0 
C) 6.2 
D) 6.4 
E) 6.6

Exam 2: Water

The pK1 of citric acid is 3.09.What is the citric acid : monosodium citrate ratio in a 1.0 M citric acid solution with a pH of 2.09?

In the energetics of transferring hydrocarbons from water to nonpolar solvents, the factor T Δ\DeltaΔ S is commonly

Kw, the ionization constant of water, is _____ at _____.

Weak acids

Matching -For the ______ represented by D-H...A, the donor D is weakly acidic and the acceptor A is weakly basic.

To make a phosphate buffer at pH 6.82 starting with one liter of 10 mM phosphoric acid (pKs are 2.15, 6.82, and 12.38), you could add

Amphiphilic molecules

Osmotic pressure is a function of

Ice

A buffer contains 0.010 mol of lactic acid (pKa = 3.86)and 0.050 mol sodium lactate per liter of aqueous solution. a.Calculate the pH of this buffer. b.Calculate the pH after 5.0 mL of 0.50 M HCl is added to 1 liter of the buffer (assume the total volume will be 1005 mL).

In a hydrogen bond between a water molecule and another biomolecule

Hydrophobic interactions between nonpolar molecules

The pH at the midpoint in the titration of an acid with a base is

Matching -The polarity of the O-H bond is caused by the ______ of oxygen relative to that of hydrogen.

Urea is a water-soluble product of nitrogen metabolism.How many hydrogen bonds can one urea molecule donate to surrounding water molecules?

The strongest noncovalent interactions are

A solution is made by mixing 0.05 mL of 1.0 M HCl with 999.95 mL of pure water.Calculate the pH of the resulting solution (assume the total volume is 1.0 L).

What is the approximate pKa of a weak acid HA if a solution 0.1 M HA and 0.3 M A- has a pH of 6.5?

Introduction to the Chemistry of Life

Nucleotides, Nucleic Acids, and Genetic Information

Amino Acids

Proteins: Primary Structure

Proteins: Three-Dimensional Structure

Protein Function Part I: Myoglobin and Hemoglobin

Carbohydrates

Lipids and Biological Membranes

Membrane Transport

Enzyme Catalysis

Enzyme Kinetics, Inhibition and Control

Biochemical Signaling

Introduction to Metabolism

Glycogen Metabolism and Gluconeogenesis

Glucose Catabolism

Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Mammalian Fuel Metabolism: Integration and Regulation

Nucleotide Metabolism

Nucleic Acid Structure

Dna Replication, Repair and Recombination

Transcription and Rna Processing

Translation

Regulation of Gene Expression

Filters

The pK₁ of citric acid is 3.09.What is the citric acid : monosodium citrate ratio in a 1.0 M citric acid solution with a pH of 2.09?

In the energetics of transferring hydrocarbons from water to nonpolar solvents, the factor T $\Delta$ S is commonly

K_w, the ionization constant of water, is _ at _.

A buffer contains 0.010 mol of lactic acid (pK_a = 3.86)and 0.050 mol sodium lactate per liter of aqueous solution. a.Calculate the pH of this buffer. b.Calculate the pH after 5.0 mL of 0.50 M HCl is added to 1 liter of the buffer (assume the total volume will be 1005 mL).

What is the approximate pK_a of a weak acid HA if a solution 0.1 M HA and 0.3 M A^- has a pH of 6.5?