Question 1

Which statement explains the cleaning action of soap on greasy dishes?

Accepted Answer

A)   The soap changes the water-solubility of the grease so that it is easily dissolved by the water.
B)   The grease is trapped inside the hydrophobic interior of micelles made of soap molecules.
C)   The soap chemically breaks down the grease into smaller, more water-soluble molecules.
D)   The soap hydrates the grease with its polar head groups and holds it in suspension.

Question 2

What is the difference between a particle being hydrated versus being solvated?

Accepted Answer

A)   A hydrated particle is surrounded by a shell of water. A solvated molecule is surrounded by a shell of solvent molecules, not necessarily water.
B)   The terms hydrated and solvated mean exactly the same thing.
C)   A hydrated particle has reacted with hydrogen. A solvated particle is dissolved in a solvent.
D)   The word hydrated is used only when the solute is an electrolyte.

Question 3

Electrolytes dissolve readily in water because

Accepted Answer

A)   they are held together by electrostatic forces.
B)   they are hydrophobic.
C)   water molecules can cluster about cations.
D)   water molecules can cluster about anions.
E)   water molecules can cluster about cations and anions.

Question 4

Hyperventilation can result in alkalosis because there is excessive loss of carbon dioxide and, therefore a loss of carbonic acid.

Accepted Answer

A) True 
 B)False

Question 5

Which is true about the solubility of electrolytes in water?

Accepted Answer

A)   They are all insoluble in water.
B)   They are usually only sparingly soluble in water.
C)   They often form super-saturated aqueous solutions.
D)   They readily dissolve and ionize in water.

Question 6

Which statement does not explain the polarity of water?

Accepted Answer

A)   Oxygen is more electronegative than hydrogen.
B)   Water molecules have a bent geometry (V-shaped) .
C)   The oxygen in water has (sp2 hybrid orbitals.
D)   In water the hydrogen carries a partial positive charge (δ+) .

Question 7

Which of the following is NOT a ʺweakʺ interaction?

Accepted Answer

A)   hydrogen bonds
B)   van der Waals forces
C)   disulfide bonds
D)   ionic interactions
E)   hydrophobic interactions

Question 8

The equilibrium constant of water Keq) is the rate that dissociation of the molecule occurs at room temperature.

Accepted Answer

A) True 
 B)False

Question 9

A solution containing 10-8 M HCl and 10-8 M acetic acid contains H+ which is supplied mostly by

Accepted Answer

A)   the strong acid.
B)   the weak acid.
C)   both the strong and the weak acids.
D)   water.
E)   All of the above

Question 10

Solutes diffuse more slowly in cytoplasm than in water because of

Accepted Answer

A)   the higher viscosity of water.
B)   the higher heat of vaporization of water.
C)   the presence of many crowded molecules in the cytoplasm.
D)   the absence of charged molecules inside cells.

Question 11

Enzymes which condense subunits of macromolecules during their synthesis usually

Accepted Answer

A)   transfer an acyl or carbonyl group to an electrophile.
B)   exclude water from the active site.
C)   contain inhibitors of hydrolases.
D)   are catalyzing thermodynamically favored reactions.
E)   All of the above

Question 12

The osmotic pressure of an aqueous solution depends on

Accepted Answer

A)   the chemical nature of the solute.
B)   the molar concentration of solute.
C)   the hydrophobic effect of the solute.
D)   All of the above.
E)   None of the above.

Question 13

The combined effect of many weak noncovalent interactions can be very significant in determining factors such as three-dimensional structure for large biological molecules.

Accepted Answer

A) True 
 B)False

Question 14

The attractive force between two atoms is maximized when they are separated by the sum of their van der Waals radii.

Accepted Answer

A) True 
 B)False

Question 15

The ion-product constant for water, Kw, is

Accepted Answer

A)   1 x 10-7 M2.
B)   1 x 10-7 M.
C)   1 x 10-14 M2.
D)   1 x 10-14 M.

Question 16

The self-ionization of water is .

Accepted Answer

A)   a unimolecular dissociation of a single water molecule to H+ and OH-
B)   a biomolecular reaction between two water molecules to yield H3O+ and OH-
C)   a result of hydrophobic interactions
D)   a termolecular reaction involving the simultaneous collision of H2O, H+ and OH-

Question 17

Pure water has a concentration of

Accepted Answer

A)   18 g/ml.
B)   1 g/ml.
C)   1000 g/ml.
D)   55 M.

Question 18

Hydrogen bonds in the interior of a protein or other macromolecule are stronger than those on the exterior.

Accepted Answer

A) True 
 B)False

Question 19

How does the ion-product of water, Kw, relate to the equilibrium constant, Keq, for the dissociation reaction of water?

Accepted Answer

A)   Kw is found by multiplying Keq by the concentration of water.
B)   Kw just another symbol for Keq , so they are equal.
C)   Kw is found by dividing Keq by the ideal gas constant.
D)   Kw is found by multiplying Keq by the concentrations of hydronium ion and hydroxide ion.

Question 20

Proteins dissolved in water can be hydrolyzed by nucleophilic attack from the water molecules.

Accepted Answer

A) True 
 B)False

Exam 2: Water

The osmotic pressure of an aqueous solution depends on

Correct AnswerverifiedShow Answer

Hyperventilation can result in alkalosis because there is excessive loss of carbon dioxide and, therefore a loss of carbonic acid.

Correct AnswerverifiedShow Answer

Hydrogen bonds in the interior of a protein or other macromolecule are stronger than those on the exterior.

Correct AnswerverifiedShow Answer

Which is true about the solubility of electrolytes in water?

Correct AnswerverifiedShow Answer

A solution containing 10-8 M HCl and 10-8 M acetic acid contains H+ which is supplied mostly by

Correct AnswerverifiedShow Answer

How does the ion-product of water, Kw, relate to the equilibrium constant, Keq, for the dissociation reaction of water?

Correct AnswerverifiedShow Answer

The combined effect of many weak noncovalent interactions can be very significant in determining factors such as three-dimensional structure for large biological molecules.

Correct AnswerverifiedShow Answer

The ion-product constant for water, Kw, is

Correct AnswerverifiedShow Answer

Electrolytes dissolve readily in water because

Correct AnswerverifiedShow Answer

What is the difference between a particle being hydrated versus being solvated?

Correct AnswerverifiedShow Answer

The attractive force between two atoms is maximized when they are separated by the sum of their van der Waals radii.

Correct AnswerverifiedShow Answer

The equilibrium constant of water Keq) is the rate that dissociation of the molecule occurs at room temperature.

Correct AnswerverifiedShow Answer

Which of the following is NOT a ʺweakʺ interaction?

Correct AnswerverifiedShow Answer

Pure water has a concentration of

Correct AnswerverifiedShow Answer

Enzymes which condense subunits of macromolecules during their synthesis usually

Correct AnswerverifiedShow Answer

Which statement does not explain the polarity of water?

Correct AnswerverifiedShow Answer

Solutes diffuse more slowly in cytoplasm than in water because of

Correct AnswerverifiedShow Answer

Which statement explains the cleaning action of soap on greasy dishes?

Correct AnswerverifiedShow Answer

Proteins dissolved in water can be hydrolyzed by nucleophilic attack from the water molecules.

Correct AnswerverifiedShow Answer

The self-ionization of water is .

Correct AnswerverifiedShow Answer

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A solution containing 10^-⁸M HCl and 10^-⁸M acetic acid contains H⁺which is supplied mostly by

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How does the ion-product of water, K_w, relate to the equilibrium constant, K_eq, for the dissociation reaction of water?

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The ion-product constant for water, K_w, is

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The equilibrium constant of water K_eq) is the rate that dissociation of the molecule occurs at room temperature.

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