West Los Angeles College » Chemistry » Chem 221 - Biochemistry for Science Majors » Fall 2021

Chem 221 - Biochemistry for Science Majors » Fall 2021 » L2 Water Part 1 of 2

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Question #1

A compound contains hydroxyl groups as its predominant functional group. Which of the following statements is true concerning this compound?

A. It should dissolve in a nonpolar solvent

B. It won't form hydrogen bonds with water

C. It lacks a hydrogen, so it acts as an acid

D. It is hydrophobic

E. It should dissolve in water

Question #2

Which one of the following functional groups does not participate in hydrogen bonding?

A. Methyl

B. Amido (amide)

C. Carboxyl

D. Hydroxyl

E. Amino

Question #3

Which of the following alcohols would be most soluble in water?

A. octanol

B. methanol

C. ethanol

D. butanol

Question #4

With respect to hydrogen bonds,

A. they are stronger than covalent bonds

B. they are what make peptide bonds

C. water does not have to be involved

D. they are stronger than disulfide bonds

Question #5

A solution with pH = 5 is __________ than a solution with pH = 7.

A. 10 times more acidic

B. 100 times more acidic

C. 10 times more basic

D. 2 times more basic

Question #6

The lone pair electrons on oxygen in a H2O molecule

A. are not important for the properties of water

B. carry a partial positive charge

C. form covalent bonds in ice

D. carry a partial negative charge

Question #7

The dissociation constant of H2O at 25° C is

A. 10^-7 M

B. 10^-14 M

C. 10^7 M

D. 10^14 M

Question #8

Weak acids generally have pKa

A. values less than 1

B. been seldom found in living systems

C. that cannot be used to buffer

D. values greater than 2

Question #9

The three-dimensional structure of macromolecules is formed and maintained primarily through non-covalent interactions. Which one of the following is not considered a non-covalent interaction?

A. Hydrophobic interactions

B. Ionic interactions

C. Carbon-carbon bonds

D. van der Waals interactions

E. Hydrogen bonds

Question #10

Osmosis is movement of a:

A. water molecule across a membrane

B. gas molecule across a membrane

C. charged solute molecule (ion) across a membrane

D. polar solute molecule across a membrane

E. nonpolar solute molecule across a membrane

Question #11

A hydronium ion:

A. is a hydrated hydrogen ion

B. is the usual form of one of the dissociation products of water in solution

C. has the structure H3O+

D. is a hydrated proton

E. All of the above are true

Question #12

A hydride ion:

A. contains two protons and two electrons and is the anion of hydrogen

B. has the structure H-, is the anion of hydrogen, and contains one protons and two electrons

C. contains two protons and two electrons and has the structure H-

Question #13

The aqueous solution with the lowest pH is:

A. 10–12 M NaOH

B. 1 M HCl

C. 2 M HCl

D. 1 M acetic acid (pKa = 4.86)

E. 1 M formic acid (pKa = 3.75)

Question #14

Salt dissolves well in water as water molecules

A. make nonpolar covalent bonds with the positively charged ions only

B. surround the ions because of their charge but do not form hydrogen bonds

C. share electrons with the ions to make polar covalent bonds

D. form hydrogen bonds with the positively and negatively charged ions

Question #15

If an ion for which the cell membrane does not have a transport protein is injected into the blood in significant amounts, which of the following would occur?

A. The blood cells would swell and eventually burst

B. The blood cells would shrivel due to osmotic movement of water out of the cell

C. Blood proteins would diffuse into the cells to compensate

D. The speed of blood flow through the vessels would increase

E. The volume of the blood would decrease

Question #16

The pKa of acid A is 4.5 and the pKa of acid B is 7.2. Acid B is a stronger acid than A.

A. TRUE

B. FALSE

Question #17

For a weak acid, low pKa means high dissociation.

A. TRUE

B. FALSE

Question #18

When crystalline substances (salts) dissolve in water, they acquire greater freedom of motion, which decreases the entropy of the system.

A. FALSE

B. TRUE

Question #19

Adding an acid to pure water decreases the [OH-]

A. FALSE

B. TRUE

Question #20

Adding an acid to pure water decreases the [H3O+]

A. TRUE

B. FALSE

Question #21

If NaOH(s) is dissolved in water, increasing the [OH-], the [H+] must decrease.

A. TRUE

B. FALSE

Question #22

In any aqueous solution at 25 °C, no matter what it contains, the product of [H+] and [OH-] must always equal 1.0 x 10-7.

A. FALSE

B. TRUE

Question #23

Hydrogen ions (H+) formed in the dissociation of water are immediately hydrated to hydronium ions (H3O+).

A. FALSE

B. TRUE

Question #24

In a phospholipid bilayer, the hydrophilic heads are exposed to outside water molecules while the hydrophobic tails inside the bilayer.

A. TRUE

B. FALSE

Question #25

Each acid has a characteristic tendency to lose its proton in an aqueous solution. The weaker the acid, the greater its tendency to lose its proton.

A. TRUE

B. FALSE

Question #26

A molecule change its ionization state by gaining or losing a proton (H+).

A. FALSE

B. TRUE

Question #27

Acetic acid is a strong acid.

A. TRUE

B. FALSE

Question #28

Sodium hydroxide is a strong base.

A. TRUE

B. FALSE

Question #29

Acetic acid has has two pKas.

A. TRUE

B. FALSE

Question #30

Many biochemical molecules are either weak acids or weak bases.

A. TRUE

B. FALSE

Question #31

When you add an acid or a base to water, the product of [H+] and [OH-] changes.

A. FALSE

B. TRUE

Question #32

If the pKa of acid A is 2 and the pKa of acid B is 4, that means that

A. A is 100 stronger than B

B. A is 200 stronger than B

C. A is 100 weaker than B

Question #33

Sulfuric acid is a weak acid.

A. TRUE

B. FALSE

Question #34

The degree of ionization of water to hydrogen ions (H+) and hydroxide ions (OH-) is considered

A. large

B. small

Question #35

The ionization of water is irreversible

A. FALSE

B. TRUE

Question #36

Of the non covalent interactions, the strongest is

A. hydrophobic interactions

B. hydrogen bonding

C. ionic bonding

Question #37

Of the non covalent interactions, the weakest is

A. hydrophobic interactions

B. hydrogen bonding

C. ionic bonds

Question #38

A. TRUE

B. FALSE

Question #39

Water has a

A. trigonal planar geometry

B. linear geometry

C. it varies

D. tetrahedral geometry

Question #40

The total number of hydrogen bonds of a water molecule is

A. 3

B. 4

C. 2

D. 2

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