Acids and Bases

Question 1

is the biological medium on Earth

Answer 1

Water

Question 2

Most cells are surrounded by water, and cells themselves are about

Answer 2

70–95% water

Question 3

The water molecule is a

Answer 3

polar molecule

Question 4

the opposite ends have opposite charges

Answer 4

polar molecule

Question 5

allows water molecules to form hydrogen bonds with each other

Answer 5

Polarity

Question 6

Polar covalent bonds in water molecules result in

Answer 6

hydrogen bonding

Question 7

Four of water’s properties that facilitate an
environment for life are

Answer 7

– Cohesive/adhesive behavior
– Ability to moderate temperature
– Expansion upon freezing
– Versatility as a solvent

Question 8

Collectively, hydrogen bonds hold water molecules together, a phenomenon called

Answer 8

cohesion

Question 9

helps the transport of water against gravity in plants

Answer 9

cohesion

Question 10

is an attraction between different substances, for example, between water and plant cell walls

Answer 10

adhesion

Question 11

different molecules attract each other

Answer 11

adhesion

Question 12

like molecules attract each other

Answer 12

cohesion

Question 13

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

Answer 13

Surface tension

Question 14

is related to cohesion

Answer 14

Surface tension

Question 15

can absorb or release a large amount of heat with only a slight change in its own temperature

Answer 15

water

Question 16

is the energy of motion

Answer 16

kinetic energy

Question 17

is a measure of the total amount of kinetic energy due to molecular motion

Answer 17

Heat

Question 18

measures the intensity of heat due to the average kinetic energy of molecules

Answer 18

Temperature

Question 19

The Solvent of Life

Answer 19

water

Question 20

is a liquid that is a homogeneous mixture of substances

Answer 20

solution

Question 21

is the dissolving agent of a solution

Answer 21

solvent

Question 22

is the substance that is dissolved

Answer 22

solute

Question 23

is one in which water is the solvent

Answer 23

aqueous solution

Question 24

Water is a versatile solvent due to its ________, which allows it to form hydrogen bonds easily

Answer 24

polarity

Question 25

When an ionic compound is dissolved in water, each ion is surrounded by a sphere of water molecules called a

Answer 25

hydration shell

Question 26

is one that has an affinity for water

Answer 26

hydrophilic substance

Question 27

is one that does not have an affinity for water

Answer 27

hydrophobic substance

Question 28

are hydrophobic because they have relatively nonpolar bonds

Answer 28

Oil molecules

Question 29

is a stable suspension of fine particles in a liquid

Answer 29

colloid

Question 30

The hydrogen atom leaves its electron behind and is transferred as a proton

Answer 30

hydrogen ion (H+)

Question 31

The molecule that lost the proton is now a

Answer 31

hydroxide ion (OH–)

Question 32

The molecule with the extra proton is now a

Answer 32

hydronium ion (H3O+)

Question 33

Concentrations of H+ and OH– are _________ in pure water

Answer 33

equal

Question 34

Adding certain solutes, called _______________, modifies the concentrations of H+ and OH

Answer 34

acids and bases

Question 35

Biologists use something called the ______________ to describe whether a solution is acidic or basic (the opposite of acidic)

Answer 35

pH scale

Question 36

is any substance that increases the H+ concentration of a solution

Answer 36

acid

Question 37

is any substance that reduces the H+ concentration of a solution

Answer 37

base

Question 38

- Devised by Sorenson (1902) - [H+] can range from 1M and 1 X 10-14M - using a log scale simplifies notation

Answer 38

pH Scale

Question 39

pH =

Answer 39

-log [H+]

Question 40

Neutral pH =

Answer 40

7.0

Question 41

The internal pH of most living cells must remain

Answer 41

close to pH 7

Question 42

are substances that minimize changes in concentrations of H+ and OH– in a solution

Answer 42

Buffers

Question 43

A buffered system consist of a

Answer 43

weak acid and its conjugate base