(Unit 1) Chapter 3: Water and the Fitness of the Environment

Question 1

What is the biological medium here on Earth?

Answer 1

Water

Question 2

_____-________ of Earth’s surface is submerged in _____

Answer 2

Three-quarters

Water

Question 3

The _______ distribution of electrons makes water a _____ molecule

Answer 3

Unequal

Polar

Question 4

Who highlights the importance of water to life? Where?

Answer 4

Lawrence Henderson

In a book: The Fitness of the Environment

Question 5

In water, the slightly ________ hydrogen is attracted to the slightly ________ oxygen of a nearby molecule

Answer 5

Positive

Negative

Question 6

What are molecules of water held together by?

Answer 6

Hydrogen bonds

Question 7

True or False:

When water is in liquid form, the hydrogen bonds are very strong

Answer 7

False, the hydrogen bonds are very fragile each about 1/20 as strong as a covalent bond

Question 8

What is the phenomenon called when hydrogen bonds hold water together?

Answer 8

Cohesion

Question 9

Define:

Adhesion

Answer 9

Clinging of one substance to another

Question 10

Define:

Surface tension

Answer 10

A measure of how difficult it is to stretch or break the surface of a liquid

Question 11

True or False:

Water has greater surface tension than most other liquids

Answer 11

True

Question 12

Define:

Kinetic energy

Answer 12

The energy of motion, anything that moves has kinetic energy

Question 13

True or False:

Heat is a form of energy

Answer 13

True

Question 14

Define:

Temperature

Answer 14

A measure of heat intensity that represents the average kinetic energy of the molecules, regardless of volume

Question 15

For a given body of matter, the amount of ____ is a measure of the matter’s total _______ energy due to motion of its _________

Answer 15

Heat
Kinetic
Molecules

Question 16

If the amount of heat is a measure of the matter’s total kinetic energy, what does the heat depend on?

Answer 16

Depends in part on the matter’s volume

Question 17

In what temperature scale does water freeze at 0 degrees and boil at 100 degrees at sea level?

Answer 17

Celsius Scale

Question 18

What is a calorie?

Answer 18

A unit of heat

Question 19

Define:

1 cal

Answer 19

The amount of heat it takes to raise the temperature of 1 g of water by 1 degrees Celsius (or the the amount of heat 1 g of water releases when cooled by 1 degrees Celsius)

Question 20

What does kcal represent?

Answer 20

Kilocalories

Question 21

Define:

1 kcal

Answer 21

The amount of heat needed to raise 1 kg of water by 1 degrees Celsius

Question 22

What is a joule?

Answer 22

An energy unit

Question 23

Convert joule to calories and calorie to joules

Answer 23

1 J = 0.239 cal

1 cal = 4.184 J

Question 24

Define:

Specific heat

Answer 24

The amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1 degrees Celsius

Question 25

State the specific heat of water

Answer 25

1 cal/g/degrees Celsius

Question 26

The transformation from a liquid to a gas is called:

Answer 26

Vaporization or evaporation

Question 27

Define: | Heat of vaporization

Answer 27

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

Question 28

True or False: | Water has a high specific heat but a low heat of vaporization

Answer 28

False, for the same reason that water has a high specific heat, it also has a high heat of vaporization relative to most other liquids

Question 29

The cooling of the surface of the liquid that remains behind after evaporation is known as:

Answer 29

Evaporative cooling

Question 30

What effect does the high amount of energy required to vaporize water have?

Answer 30

Helps moderate Earth's climate

Question 31

What effect does the evaporative cooling of water have?

Answer 31

Contributes to the stability of temperature in lakes and ponds and provides a mechanism that prevents terrestrial organisms from overheating

Question 32

Define: | Solution

Answer 32

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

Question 33

Define: | Solvent

Answer 33

The dissolving agent of a solution

Question 34

Define: | Solute

Answer 34

The substance that is dissolved in a solution

Question 35

Define: | Aqueous solution

Answer 35

A solution which water is the solvent

Question 36

Define: | Hydration shell

Answer 36

The sphere of water molecules around each dissolved ion

Question 37

True or False: | Compounds have to be ionic to dissolve in water

Answer 37

False, compounds do not have to be ionic to dissolve in water (e.x. sugar)

Question 38

Explain what water molecules do to a table salt molecule (2)

Answer 38

The oxygen region of water attracts to the positively charged ion (sodium), forming a hydration shell The hydrogen region of water attract to the negatively charged ion (chlorine), forming another hydration shell

Question 39

Any substance that has an affinity for water is said to be:

Answer 39

Hydrophilic

Question 40

Define: | Colloid

Answer 40

A stable suspension of fine particles in a liquid

Question 41

When a substance is hydrophobic, what properties does it have? (2)

Answer 41

Non-ionic, non-polar (or some other reason cannot form hydrogen bonds) Seem to repel water

Question 42

Define: | Molecular Mass

Answer 42

The sum of the masses of all the atoms in a molecule

Question 43

Biological chemistry is "___" chemistry

Answer 43

Wet

Question 44

What does a mole represent?

Answer 44

An exact number of objects (6.02 * 10^23)

Question 45

What is the number of objects in a mole known as?

Answer 45

Avogradro's number

Question 46

How many daltons are in 1 gram?

Answer 46

6.02 * 10^23 (Avogadro's Constant)

Question 47

Define: | Molarity

Answer 47

The number of moles of solute per liter of solution

Question 48

If sucrose has a molecular mass of 342 daltons, how grams does 1 mol of sucrose weigh?

Answer 48

342 grams

Question 49

What is a hydrogen ion?

Answer 49

A single proton with a charge of +1

Question 50

What is a hydroxide ion?

Answer 50

An oxygen and hydrogen ion with a charge of -1

Question 51

Occasionally, the hydrogen atom participating in a hydrogen bond between two water molecules shifts from on molecule to the other. Explain this reaction

Answer 51

Originally, 2 water molecules are attracted via a hydrogen bond Now, the hydrogen ion (proton) of one water molecule binds to the other water molecule to form a hydronium ion (H3O+), leaving a hydroxide ion (OH-)

Question 52

Define: | Acid

Answer 52

A substance that increases the hydrogen ion concentration of a solution

Question 53

Define: | Base

Answer 53

A substance that reduces the hydrogen ion concentration of a solution

Question 54

True or False: | The conversion of water to hydronium and hydroxide ions is a reversible reaction

Answer 54

True

Question 55

What do biologists use to describe how acidic or basic something is?

Answer 55

pH scale

Question 56

True or False: | The dissociation of water is common and can change the acidity of the water

Answer 56

False, the dissociation of water is statistically rare and only adding certain kinds of solutes can change how acidic/basic the water is

Question 57

How do acids increase the hydrogen ion concentration of a solution?

Answer 57

When acids dissolve in water, they donate additional H+ to the solution

Question 58

How do bases reduce the hydrogen ion concentration of a solution? (2)

Answer 58

Some accept hydrogen ions (e.x. Ammonia) | Some dissociate, forming hydroxide ions that combine with hydrogen ions to form water (e.x. Sodium hydroxide)

Question 59

What is the difference between a strong base/acid and a weak base/acid?

Answer 59

Strong base/acid dissociates completely when mixed with water Weak base/acid reactions with water is reversible (e.x. Ammonia can accept H+ and then release H+)

Question 60

In any aqueous solution at __ degrees Celsius, the product of the __ and ___ concentrations is constant at __^___. This can be written as:

Answer 60

``` 25 H+ OH- 10^-14 [H+][OH-] = 10^-14 ```

Question 61

What is the pH of a solution defined as?

Answer 61

The negative logarithm (base 10) of the hydrogen ion concentration

Question 62

As pH increases, H+ concentration ________

Answer 62

Declines

Question 63

If the solution of a pH is 10, what is the concentration of the hydroxide ions?

Answer 63

10^-4 M

Question 64

In molarity, what is how is a 1 mol/L solution indicated?

Answer 64

1 M solution

Question 65

Define: | Buffers

Answer 65

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

Question 66

What is an example of a buffer? State the reaction that this buffer undergoes

Answer 66

Carbonic acid (H2CO3), formed when CO2 reacts with water in blood plasma) When H+ concentration in blood falls, the carbonic acid dissociates to replenish hydrogen ions When H+ concentration in blood rises, the bicarbonate combines with the H+ to form carbonic acid again

Question 67

Define: | Acid precipitation

Answer 67

Rain, snow, or fog with a pH lower (more acidic) than pH 5.2

Question 68

What is the pH of uncontaminated rain around?

Answer 68

5.6

Question 69

Define: | Calcification

Answer 69

The production of calcium carbonate (CaCO3) by corals and other organisms

Question 70

What is the calcification in corals and such related to?

Answer 70

The levels of CO3(2-) in the water

Question 71

When CO2 dissolves in seawater, it reacts with water to form what?

Answer 71

Carbonic acid

Question 72

Almost all carbonic acid in seawater dissociates into what two ions?

Answer 72

Bicarbonate (HCO3-) and Carbonate (CO3(2-))