Chapter 2 - Water

Question 1

What hybridization is the oxygen atom in water? Leads to what?

Answer 1

sp3 hybridized; Leads to a tetrahedral electron domain geometry (109.5 degrees)

Question 2

The presence of two lone pairs results in a ___ molecular geometry (H–O–H, θ = ____)

Answer 2

bent; 104.5°

Question 3

What is the most abundant cell in all living cells? What percentage?

Answer 3

Water; 60-90% by mass

Question 4

Describe the hydrolysis of water.

Answer 4

Slow, most are thermodynamically favorable (–ΔG).

Question 5

What kind of bonding interaction does hydrogen have in water?

Answer 5

Strong dipole-dipole interaction of hydrogen bonding.

Question 6

Diffusion rates of small molecules (~__%) in cells are ____ impacted vs. large molecules (~__-__%), relative to pure water.

Answer 6

75; less; 5-10

Question 7

Does solute tend to be higher or lower within cells relative to their surrounding areas? Causes what?

Answer 7

Higher; water to diffuse into cells

Question 8

Define osmosis.

Answer 8

The process where a solvent diffuses through a semi-impermeable membrane from a region of lower solute concentration to a region of higher solute concentration.

Question 9

Why is osmotic pressure required?

Answer 9

It is the pressure required to prevent osmosis.

Question 10

The hydrophobic effect is responsible for…

Answer 10

self-assembly of amphipathic compounds in aqueous solution, can form micelles, monolayers, or bilayers and improve solubility of nonpolar solutes.

Question 11

List 2 things about noncovalent interactions.

Answer 11

H-bond, charge-charge interactions are electrostatic interactions b/w 2 charged particles

Question 12

NONCOVALENT INTERACTIONS: What is a salt bridge?

Answer 12

Ion pairing between oppositely-charged functional groups.

Question 13

NONCOVALENT INTERACTIONS: Define Van der Waals forces.

Answer 13

Interactions b/w molecules with permanent or transient dipole moments (attractive or repulsive).

Question 14

NONCOVALENT INTERACTIONS: Describe hydrophobic interactions.

Answer 14

Interactions b/w nonpolar regions or molecules; Individually-weak interactions (~3kJ/mol)

Question 15

What is the acid-dissociation constant (Ka)?

Answer 15

The equilibrium constant for the ionization of an acid in water.

Question 16

What is the Henderson–Hasselbalch Equation?

Answer 16

pH = pKa + log ([base]/[acid])

Question 17

How are buffers prepared?

Answer 17

Prepared from a weak acid and its conjugate base, an aqueous solution which resists changes in pH.

Question 18

Define buffer capacity.

Answer 18

The amount of acid (or base) that can be added to a buffer solution without large pH changes.

Question 19

How is the buffer capacity determined?

Answer 19

By the CA and CB - the more concentrated the buffer solution,
the greater the buffer capacity

Question 20

What is primarily responsible for
the buffer capacity of blood plasma?

Answer 20

The carbonic acid–bicarbonate–carbonate buffer system.

Question 21

pKa1 of H2CO3 is ___, close to the target buffer of pH ___.

Answer 21

6.4; 7.4