Chapter 2 (Water)

Question 1

Water is the…

Answer 1

biological medium on Earth

Reactions, etc. happen in water

Question 2

Cell weight is…water?

Answer 2

75%

Question 3

Water has an…charge distribution

Answer 3

unequal

Each water molecule can form up to four hydrogen bonds with other water molecules

Question 4

What are the three physical states of matter?

Answer 4

Solid
Liquid
Gas

Question 5

What type of bonds is found in water?

Answer 5

Polar covalent bonds

The uneven distribution of charge on the molecule facilitates Hydrogen Bonding

Question 6

Hydrogen Bonds in water is about…the strength of a covalent bond

Answer 6

1/20

Question 7

Four Properties of Water Facilitate Life

Answer 7

1. Highly cohesive and adhesive
2. Temperature moderation
3. Low density of ice
4. Ability to dissolve other substances

Question 8

Cohesion of Water Molecules

Answer 8

Water evaporates from top of tree
Pulls water upward from roots

Special cells transport water up the tree
Xylem

The adhesion of water to the cell wall and cohesion to other water molecules helps resist the pull of gravity

Question 9

Surface Tension

Answer 9

Measure of how hard it is to break the surface of a liquid

Water has unusually high surface tension due to hydrogen bonding between the molecules at the air-water interface and to the water below

Question 10

Temperature Moderation

Answer 10

Evaporation is transformation of a substance from liquid to gas

Heat of vaporization is the heat a liquid must absorb for 1 g to be converted to gas

As a liquid evaporates, its remaining surface cools, a process called evaporative cooling

Evaporative cooling of water helps stabilize temperatures in organisms and bodies of water

Question 11

Floating of Ice on Water

Answer 11

Ice is less dense than water

Ice floats in liquid water because hydrogen bonds in ice are more “ordered” making ice less dense than water

Question 12

Water is the…of life

Answer 12

solvent

Water is a polar solvent

Question 13

Solution

Answer 13

Liquid that is a completely homogeneous mixture of substances

Question 14

Solvent

Answer 14

The dissolving agent of a solution

Water is a polar solvent

Question 15

Solute

Answer 15

The substance that is dissolved

Question 16

Aqueous Solution

Answer 16

One in which water is the solvent

Question 17

Water is a polar solvent

Answer 17

Unequal charge distribution allows it to dissolve many ionic compounds

Positive region of water molecules surround negative ions

Negative regions surround positive ions

Question 18

Hydrophilic and Hydrophobic Substances

Answer 18

A hydrophilic substance is one that has an affinity for water
Tend to be polar or have polar covalent bonds
Salt and sugar

A hydrophobic substance is one that does not have an affinity for water
Are non-polar
Oils and fats

Question 19

Buffers

Answer 19

Substances that minimize changes in concentrations of H+ and OH- in a solution

The internal pH of most living cells must remain close to pH 7

Most buffer solutions contain a weak acid and its corresponding base, which combine reversibly with H+ ions