Chapter 2 section 1

Question 1

What happens when water ionizes?

Answer 1

t forms H⁺ and OH⁻ (H₂O ⇌ H⁺ + OH⁻).

Question 2

What is the hydrated form of H⁺ in water?

Answer 2

H₃O⁺ (hydronium ion).

Question 3

Why is water’s ionization important?

Answer 3

it establishes the basis for pH and acid–base chemistry in biology.

Question 4

What makes water such a good solvent?

Answer 4

Its polarity and ability to form hydrogen bonds

Question 5

How do nonpolar molecules affect water entropy?

Answer 5

They decrease entropy; when they cluster, solvent entropy increases (hydrophobic effect).

Question 6

What is an amphiphilic molecule?

Answer 6

A molecule with both hydrophilic (polar) and hydrophobic (nonpolar) regions (e.g., sodium palmitate)

Question 7

What structure do amphiphiles form in water?

Answer 7

Micelles, with hydrophobic tails inside and hydrophilic heads outside.

Question 8

What is osmotic pressure of a 1 molal solution?

Answer 8

About 22.4 atm.

Question 9

What happens when a nonpolar solute is placed in water?

Answer 9

Water forms an ordered H-bond network around it, decreasing entropy.

Question 10

Why are hydrophobic interactions entropically unfavorable?

Answer 10

non-polar molecules force surrounding water molecules into ordered, structured “clathrate cages” these cages increase order. and decrease entropy

Question 11

What term describes molecules with both polar and nonpolar parts?

Answer 11

Amphiphilic (or amphipathic).

Question 12

How do amphiphilic molecules interact with solvents?

Answer 12

Favorably with both polar and nonpolar environments

Question 13

Give an example of an amphiphilic molecule.

Answer 13

Fatty acids.

Question 14

What structure can water form around nonpolar solutes?

Answer 14

A clathrate cage of ordered H-bonded molecules.

Question 15

How many H-bonds per molecule in ice vs. liquid water?

Answer 15

Ice: 4; Water: ~2–3.

Question 16

How stable are H-bonds in ice compared to water?

Answer 16

ce: long-lived; Water: very short-lived (constantly breaking/reforming).

Question 17

What does the H-bond network in liquid water look like?

Answer 17

A dynamic, fluid network

Question 18

Why does water dissolve ions well

Answer 18

High dielectric constant reduces electrostatic interactions

Question 19

What surrounds ions in water?

Answer 19

water molecules.(hydration)

Question 20

How does water interact with polar solutes?

Answer 20

Forms hydrogen bonds with them

Question 21

What is a key interaction that occurs bc of water’s polar nature on nonpolar solutes

Answer 21

Drives hydrophobic interactions.

Question 22

What unusual physical properties does water have?

Answer 22

High boiling point, melting point, heat of vaporization, and surface tension.

Question 23

What makes water polar?

Answer 23

Its bent molecular structure.

Question 24

What is unusual about water’s bond angles?

Answer 24

They are non-tetrahedral.

Question 25

does water act as a donor or an acceptor in hydrogen bonding.

Answer 25

As both a donor and an acceptor.

Question 26

How many hydrogen bonds can each water molecule form?

Answer 26

Up to four.