Chapter 2: Water, the Solvent of Life

Question 1

What are important properties of water?

Answer 1

1. Polar protic solvent
2. Dissolves ions and polar molecules
3. Is amphoteric (weak acid and weak base)
4. Is a weak nucleophile
5. Liquid over wide range of temperature
6. Ice is less dense than liquid water

Question 2

How does the ability to form hydrogen bonds make water an important solvent?

Answer 2

Hydrogen bonding gives water a high boiling point, a high melting point, and strong surface tension.

Question 3

What does water do when its around nonpolar groups?

Answer 3

It forms a cage!
- Ex. lipid bilayers

Question 4

What is the hydrophobic effect?

Answer 4

When nonpolar solutes (or nonpolar parts of amphipathic solutes) will separate out from water and associate with one another in aqueous solution.

Question 5

What are colligative properties (boiling point, melting point, osmolarity) affected by?

Answer 5

The concentration of a solute.

Question 6

What is an acid?

Answer 6

A proton (H+) donor.

Question 7

What is a base?

Answer 7

A proton (H+) acceptor

Question 8

What is the dissociation of acids quantified by?

Answer 8

pKa = -logKa

Question 9

What is a buffer solution?

Answer 9

An aqueous solution of a weak acid and its conjugate base in nearly equimolar amounts.
- Resists changes in pH when small amounts of H+ or OH- are added.

Question 10

What is the Henderson-Hasselbach Equation?

Answer 10

pH = pKa + log ([A-]/[HA])

Question 11

What biological pH’s are regulated by buffers?

Answer 11

The cytoplasm and blood plasma