Chapters 3 & 4

Question 1

Water molecules have a polarity, which allows them to be electrically attracted to other water molecules and other polar molecules by weak chemical bonds known as _____.

Answer 1

hydrogen bonds

Question 2

Many of water’s emergent properties, such as its cohesion, its high specific heat, and its high heat of vaporization, result from the fact that water molecules _____.

Answer 2

are attracted to each other by partial negative and positive charges on the oxygen and hydrogen atoms, respectively

Question 3

The amount of energy that must be absorbed or lost to raise or lower the temperature of 1 g of liquid water by 1°C _____.

Answer 3

is 1 calorie

Question 4

Because organisms are made primarily of water, they resist rapid temperature changes. This useful quality is based on water’s _____.

Answer 4

high specific heat

Question 5

Water has a high specific heat, meaning that

Answer 5

a relatively large amount of heat must be added or removed in order to get the temperature of the water to change significantly.

Question 6

The specific heat of liquid water is

Answer 6

1 cal/g/°C

Question 7

The formation of hydrogen bonds between the positive and negative regions of different water molecules accounts for

Answer 7

most of water’s unique properties.

Question 8

The polarity of a water molecule allows the oxygen of one water molecule to

Answer 8

bond weakly to the hydrogen of another water molecule.

Question 9

Sodas typically contain sugar, flavorings, coloring agents, and carbon dioxide dissolved in water. The best term to describe this mixture would be _____.

Answer 9

an aqueous solution

Question 10

If the molecular mass of a carbon atom is 12, the mass of a hydrogen atom is 1, and the mass of an oxygen atom is 16 daltons, how many molecules does one mole of table sugar (sucrose; C12H22O11) contain?

Answer 10

6.02 x 10^23

Question 11

the number of molecules in one mole of any substance is

Answer 11

6.02 x 10^23

Question 12

An acid is a substance that _____.

Answer 12

increases the hydrogen ion concentration of an aqueous solution

Question 13

As an acid dissociates, it

Answer 13

donates a hydrogen ion to the solution

Question 14

A pH of 6 is how many times more acidic than a pH of 9?

Answer 14

1,000

Question 15

A pH of 6 is

Answer 15

10 times more acidic than 7, which is 10 times more acidic than 8, which is 10 times more acidic than 9. 10 x 10 x 10 = 1,000.

Question 16

A buffer

Answer 16

resists change in pH by accepting hydrogen ions when acids are added to the solution and donating hydrogen ions when bases are added.

Question 17

Buffers minimize the change in the _____ of a solution.

Answer 17

pH

Question 18

Most acid precipitation results from the combination of _____ with water in the atmosphere, forming strong acids that fall with rain or snow.

Answer 18

sulfur oxides and nitrogen oxides.

These compounds react with water in the atmosphere to form sulfuric acid and nitric acid.

Question 19

Most organic compounds contain carbon and _____.

Answer 19

hydrogen

Question 20

The experiments of Wöhler, Kolbe, Miller, and other chemists invalidated the concept of vitalism by demonstrating that _____.

Answer 20

organic molecules could be produced apart from living organisms using inorganic materials

Question 21

Vitalism gave way to mechanism, the view that _____.

Answer 21

physical and chemical laws govern living systems

Living things are subject to physical and chemical laws. They do not exist outside of them.

Question 22

The large diversity of shapes of biological molecules is possible because of the extensive presence of _____ in the molecules.

Answer 22

carbon

With four electrons to share, carbon-based molecules can be multibranching and three-dimensionally variable.

Question 23

Which of the following is a hydrocarbon?

Answer 23

C3H8

(This is a typical hydrocarbon with single covalent bonds; the number of hydrogen atoms is equal to two times the number of carbon atoms plus 2.)

Question 24

Molecules that have the same chemical formula (same numbers of each atom) but different three-dimensional shapes are called _____.

Answer 24

isomers

Isomers of carbon compounds can arise in several different ways.

Question 25

Cis-trans isomers

Answer 25

differ in their spatial arrangement around inflexible double bonds.

(Cis-trans isomers maintain the same covalent partnerships, but the atoms may be arranged differently.)

Question 26

Citric acid makes lemons taste sour. Which of the following is a functional group that would cause a molecule such as citric acid to be acidic?

Answer 26

carboxyl

The carboxyl group can release a hydrogen ion when in solution.

Question 27

Variations in the reactive properties of different organic molecules are most closely associated with _____.

Answer 27

the presence or absence of functional groups.

Question 28

Functional groups are the most common participants in

Answer 28

chemical reactions

Question 29

What functional group is commonly used in cells to transfer energy from one organic molecule to another?

Answer 29

phosphate.

(The addition and release of phosphate groups to and from ADP and ATP is how cells store chemical energy and expend it to accomplish work.)

Question 30

Each water molecule is joined to _____ other water molecules by ____ bonds.

Answer 30

four … hydrogen

(As can be seen in the illustration on page 1 of the activity titled “The Polarity of Water” a water molecule is joined to four other water molecules by hydrogen bonds.)

Question 31

The unequal sharing of electrons within a water molecule makes the water molecule _____.

Answer 31

polar

(The electrons spend more time with the oxygen of the water molecule than with the hydrogens of water. Thus, the oxygen has a net negative charge and the hydrogens have a net positive charge.)

Question 32

The tendency of an atom to pull electrons toward itself is referred to as its _____.

Answer 32

electronegativity

Question 33

Hydrogen Bonds are weaker than covalent bonds because

Answer 33

they do not involve sharing of electrons, and they are weaker than ionic bonds because they involve the attraction of partial (not full) opposite charges.

Question 34

The high surface tension of water allows

Answer 34

the insect to remain on the surface.

Question 35

Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature?

Answer 35

the absorption of heat by the breaking of hydrogen bonds

Question 36

The bonds that are broken when water vaporizes are

Answer 36

hydrogen bonds between water molecules

Question 37

Which of the following is a hydrophobic material?

Answer 37

wax

Question 38

We can be sure that a mole of table sugar and a mole of vitamin C are equal in their

Answer 38

number of molecules

Question 39

Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake?

Answer 39

10^-4 M

Question 40

A slice of pizza has 500 kcal. If we could burn the pizza and use all the heat to warm a 50-L container of cold water, what would be the approximate increase in the temperature of the water? (Note: A liter of cold water weighs about 1 kg.)

Answer 40

10 degrees C

Question 41

How many grams of acetic acid (C2H4O2) would you use to make 10 L of a 0.1 M aqueous solution of acetic acid? (Note: The atomic masses, in daltons, are approximately 12 for carbon, 1 for hydrogen, and 16 for oxygen.)

Answer 41

60 g

Question 42

Organic chemistry is currently defined as

Answer 42

the study of carbon compounds

Question 43

Which chemical group is most likely to be responsible for an organic molecule behaving as a base?

Answer 43

amino