Chapter 3: Water and Life

Question 1

Polar Covalent Bonds

Answer 1

unequal sharing of electrons

Question 2

Polar Molecule

Answer 2

overall charge is unevenly distributed

Question 3

Hydrogen Bond

Answer 3

the partially positive hydrogen of one molecule is attracted to the partially negative oxygen of nearby molecule

Question 4

Structure and Function

Answer 4

extraordinary properties of water emerge from the hydrogen bond

Question 5

Cohesion

Answer 5

the hydrogen bonds hold the substance together

Question 6

4 Emergent Properties of Water

Answer 6

cohesive behavior; ability to moderate temperature; expansion; versatility as a solvent

Question 7

Adhesion

Answer 7

clinging of one substance to another (adhesion of water by hydrogen bonds to the molecules of cell walls helps counter downward pull of gravity)

Question 8

Surface Tension

Answer 8

measure of how difficult it is to stretch or break surface of liquid (hydrogen-bonded to one another and to water below, and not to air)

Question 9

Specific Heat

Answer 9

amount of heat absorbed/lost for 1g to change 1 Celsius (when water change its temperature, it absorbs or loses a relatively large quantity of heat for each degree change)

Question 10

Specific Heat & Hydrogen Bond

Answer 10

heat must be absorbed in order to break hydrogen bonds; heat is released when hydrogen bonds form

Question 11

Relevance of Water Specific Heat

Answer 11

because of its high specific heat, the water that covers most Earth keeps temperature fluctuation on land and in water within limits that permit life (absorb heat from air that is warmer and release heat for air that is cooler)

Question 12

Kinetic Energy

Answer 12

the energy of motion

Question 13

Thermal Energy

Answer 13

kinetic energy associated with the random movement of atoms (total kinetic energy/includes volume)

Question 14

Temperature

Answer 14

average kinetic energy of the molecules in a body of matter, regardless of volume

Question 15

Heat

Answer 15

thermal energy in transfer from one body of matter to another

Question 16

Calorie

Answer 16

amount of heat it takes to raise the temperature of 1g of water by 1 C

Question 17

Kilocalorie

Answer 17

amount of heat it takes to raise the temperature of 1kg by 1 C

Question 18

Heat of Vaporization

Answer 18

amount of heat a liquid must absorb for 1 g of it to be converted from liquid to gaseous state

Question 19

Water’s High Heat of Vaporization

Answer 19

resulting from the strength of its hydrogen bonds, which must be broken before the molecules can exit from the liquid in the form of water vapor

Question 20

Evaporative Cooling

Answer 20

as a liquid evaporates, the surface of the liquid that remains behind cools down because hottest molecules leave as gas (temperature decreases)

Question 21

Floating Ice on Liquid Water

Answer 21

At temperatures above 4 C, water behaves like other liquids, expanding as it warms and contracting as it cools. [Read text for explanation and significance for bodies of water]

Question 22

Solution

Answer 22

a liquid that is completely homogeneous mixture of two or more substances

Question 23

Solvent

Answer 23

dissolving agent of a solution

Question 24

Solute

Answer 24

substance that is dissolved

Question 25

Aqueous Solution

Answer 25

solute is dissolved in water

Question 26

Hydration Shell

Answer 26

due to polarity, water molecules form sphere around each dissolved ion (Na+ and Cl-)

Question 27

Hydrophillic

Answer 27

substance has an affinity with water

Question 28

Hydrophobic

Answer 28

substances that are nonionic and nonpolar seem to repel water

Question 29

Hydrogen Ion

Answer 29

hydrogen atom leaves water molecule leaving an electron behind (cation H+/always associated with hydronium ion)

Question 30

Hydroxide Ion

Answer 30

water molecule that lost proton (hydrogen ion/cation) OH-

Question 31

Hydronium Ion

Answer 31

hydrogen ion binds to water molecule (H3O+)

Question 32

Base

Answer 32

substance that reduces the hydrogen ion concentration of a solution

Question 33

Acid

Answer 33

a substance that increases hydrogen ion concentration of a solution

Question 34

pH Scale

Answer 34

acid = H+ > OH-
base = H+ < OH-

Question 35

Buffer

Answer 35

substance that minimizes changes in the concentrations of H+ and OH- in a solution

Question 36

Ocean Acidification

Answer 36

when CO2 dissolves in seawater, it reacts with water to form carbonic acid, which lowers ocean pH