Deck 2: Aqueous Chemistry

Question 1

At any given moment, a single water molecule participates in _____ strong hydrogen bond(s). The role played by the water molecule is best characterized as _____.

A) two ; one H-bond donor, one H-bond acceptor
B) two ; two H-bond donor
C) two ; two H-bond acceptor
D) one; H-bond donor
E) one; H-bond acceptor

Answer 1

two ; one H-bond donor, one H-bond acceptor

Question 2

The strongest non-covalent interactions are _____.

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

Answer 2

ionic interactions

Question 3

Hydrogen bonds are approximately _____% of the bond strength of covalent C-C or C-H bonds.

A) 1
B) 5
C) 20
D) 50
E) 95

Answer 3

5

Question 4

When a non-polar substance is added to water, how do the molecules of water behave?

A) the regular hydrogen bond pattern is disrupted resulting in a decrease of entropy
B) the regular hydrogen bond pattern is disrupted resulting in an increase of entropy
C) the regular hydrogen bond pattern is disrupted resulting in a decrease of enthalpy
D) the regular hydrogen bond pattern is disrupted resulting in an increase of enthalpy
E) none of the above

Question 5

What term is used to describe the exclusion of nonpolar substances from an aqueous solution?

A) nonpolar effect
B) lipid effect
C) hydrophobic effect
D) oil droplet effect
E) amphiphilic effect

Question 6

Which of the following is an example of the hydrophobic effect?

A) the lipid membrane of cells and organelles
B) protein folding that places hydrophobic amino acids in the interior of the protein
C) the separation of salad dressing
D) oil sheens seen on the ocean following an oil spill
E) all of the above

Question 7

Which of the following explains the attractive forces between hydrophobic molecules in an aqueous solution?

A) in an aqueous environment, London dispersion forces between hydrophobic molecules become stronger
B) in an aqueous environment, London dispersion forces between hydrophobic molecules and water become stronger
C) since nonpolar molecules do not form hydrogen bonds with hydrogen bonds with water, they can form hydrogen bonds with other nonpolar molecules
D) there is no increase in attractive forces between nonpolar molecules in an aqueous environment
E) none of the above

Question 8

Considering the energetics of transferring nonpolar molecules from water to a nonpolar solvent, the factor T $\Delta$ S is generally _____, causing $\Delta$ G to be _____.

A) positive; negative
B) negative; negative.
C) positive; positive
D) positive; positive.
E) negligible; either positive or negative

Question 9

A molecule that has both a polar and nonpolar region is called _____________.

A) micelleic
B) amphiphilic
C) endergonic
D) a membrane
E) none of the above

Question 10

Which of the following is an example of an amphipathic molecule?

A) adenine, a base found in nucleic acids
B) glucose, a monosaccharide
C) serine, an amino acid
D) palmitic acid, a fatty acid
E) none of the above

Question 11

Fatty acid anions most commonly assemble into _____ in aqueous solution.

A) lipid bilayers
B) solvent-filled vesicles
C) micelles
D) liposomes
E) none of the above

Question 12

Which of the following molecules would be prevented from readily crossing a lipid bilayer?

A) glucose
B) sodium ions
C) potassium ions
D) water
E) all of the above

Question 13

In an aqueous solution, if the [OH^-] is 3.0 * ^-5 M, what is the [H⁺]?

A) 7.0 *10 ^-9
B) 7.0 * 10^-2
C) 3.3 * 10^-3
D) 3.3 * 10^-10
E) none of the above

Question 14

What is the [H⁺] of an aqueous solution with a pH of 6.2?

A) 6.2 * ^-6
B) 1.6 * 10^-8
C) 6.3 * 10^-7
D) 3. 3 * 10^-5
E) none of the above

Question 15

What would be the resulting pH if one drop (0.05 ml) of 1.0 M HCl was added to one liter of pure water (assume pH 7.0)?

A) 2.7
B) 4.3
C) 5.0
D) 7.0 (there would be no significant change)
E) 9.7

Question 16

If the pK values for phosphoric acid are 2.15, 6.82 and 12.38, at what pH would one observe equal amounts of H₂PO₄^- and HPO₄^2-?

A) 2.15
B) 4.49
C) 6.82
D) 9.60
E) 12.38

Question 17

If 1.0 mL of 1.0 M acetic acid (pK = 4.76, K = 1.74 x 10^-5) was added to one liter of pure water, what is the resulting pH?

A) 1.0
B) 1.3
C) 3.0
D) 3.9
E) 10.1

Question 18

Considering a 0.1 M formic acid buffer, what is the concentration of formic acid present in a solution of pH 4.25 if the pK of formic acid is 3.75?

A) 0.024 M
B) 0.033 M
C) 0.067 M
D) 0.076 M
E) none of the above

Question 19

Which of the following shows the buffer that is found in the blood stream?

A) H₃PO₄ H₂PO₄^2- + H⁺
B) H₂PO₄^- HPO₄^2- + H⁺
C) HPO₄^2- PO₄^3- + H⁺
D) H₂CO₃ HCO₃^- + H⁺
E) HCO₃^- CO₃^2- + H⁺

Question 20

Which of the following shows the intracellular buffer?

A) H₃PO₄ H₂PO₄^2- + H⁺
B) H₂PO₄^- HPO₄^2- + H⁺
C) HPO₄^2- PO₄^3- + H⁺
D) H₂CO₃ HCO₃^- + H⁺
E) HCO₃^- CO₃^2- + H⁺

Question 21

Which of the following could be used to formulate 100 mls of a 0.10 M acetate buffer (pK=4.76) at pH 5 if you start with 64 mls of 0.10 M sodium acetate?

A) 3.6 mls of 1 M HCl
B) 3.6 mls of 1 M NaOH
C) 34 mls of 0.10 M HCl
D) 34 mls of 0.10 M NaOH
E) 34 mls of 0.10 M acetic acid

Question 22

Which of the following could be used to formulate 100 mls of a 0.10 M phosphate buffer (pK=6.82) at pH 7.2?

A) 2.9 mmoles of Na₂HPO₄ and 7.1 mmoles of NaHPO₄
B) 10 mmoles of Na₂HPO₄ and 7.1 mmoles of NaOH
C) 10 mmoles of NaHPO₄ and 7.1 mmoles of HCl
D) 10 mmoles of H₃PO₄ and 17.1 mmoles of NaOH
E) all of the above

Question 23

What is the resulting pH if 10 millimoles of HCl is added to 1 liter of a 0.1 M phosphate buffer at pH 7.00 (pK=6.82)?

A) 6.82
B) 6.98
C) 7.01
D) 7.19
E) cannot be determined

Question 24

During vigorous exercise, hydrogen ions are produced within cells as a result of increased metabolism. What component of the intracellular buffer would increase as a result of the increased H⁺ production?

A) H₃PO₄
B) H₂PO₄^-
C) HPO₄^2-
D) PO₄^3-
E) none of the above

Question 25

The most common disorder of acid-base chemistry in the human body is metabolic alkalosis.

Question 26

Which of the following can cause metabolic acidosis?

A) shock
B) overproduction of mineralcorticoids
C) slow, shallow breathing
D) renal failure
E) central nervous system depression

Question 27

During metabolic acidosis, ___ ventilation excretes acid in the form of ___.

Question 28

The amino acid ___ is metabolized in the kidney to produce ___ molecules of ammonia.

Question 29

Free amine groups are excreted as the ammonium ion, NH₄⁺, and thus help to lower blood pH.

Question 30

Metabolic alkalosis most commonly results from ___ or ___.

Question 31

The 104.5° bond angle in the water molecule is the result of the ______ of electron orbitals around oxygen.