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Cambell Bio Ch 1 > Chapter 3 > Flashcards

Chapter 3 Flashcards

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1
Q

in a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by

A

polar covalent bonds

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2
Q

the slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. what is this attraction called?

A

a hydrogen bond

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3
Q

the partial negative charge in a molecule of water occurs because

A

the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus then around the hydrogen atom nucleus

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4
Q

sulfur is in the same column of the periodic table as oxygen, but has electronegativity similar to carbon. Compared to water molecules, molecules of H2S

A

will not form hydrogen bonds with each other

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5
Q

water molecules are able to form hydrogen bonds with

A

compounds that have polar covalent bonds

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6
Q

Which of the following effects is produced by the high surface tension of water?

A

a water strider can walk across the surface of a small pond

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7
Q

Which of the following takes place as an ice cube cools a drink?

A

kinetic energy in the drink decreases

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8
Q

A dietary calorie equals 1 kilocalorie. Which of the following statements correctly defines 1 kilocalorie?

A

1000 calories, or the amount of heat required to raise the temperature of 1 kg of water by 1 degree C

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9
Q

The nutritional information on a cereal box shows that one serving of a dry cereal has 200 kilocalories. If one were to burn one serving of the cereal, the amount of heat given off would be sufficient to raise the temperature of 20 kg of water by how many degrees C?

A

10 degrees C

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10
Q

Liquid water’s high specific heat is mainly a consequence of the

A

absorption and release of heat when hydrogen bonds break and form

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11
Q

Which type of bond must be broken for water to vaporize?

A

hydrogen bonds

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12
Q

Temperature usually increases when water condenses. Which behavior of water is most directly responsible for this phenomenon?

A

the release of heat by the formation of hydrogen bonds

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13
Q

Why does evaporation of water from a surface cause cooling of the surface?

A

the water molecules with the most heat energy evaporate more readily

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14
Q

Why does ice float in liquid water?

A

hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water

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15
Q

Hydrophobic substances such as vegetable oil are

A

nonpolar substances that repel water molecules

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16
Q

One mole (mol) of glucose (molecular mass= 180 daltons) is

A

both 180 grams of glucose and 6.02 x10^23 molecules of glucose

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17
Q

How many molecules of glucose (C6H12O6 molecular mass= 180 daltons) would be present in 90 grams of glucose?

A

(90/180) x 6.02x10^23

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18
Q

How many molecules of glycerol (C3H6O3; a molecular mass=92) would be present in 1 L of a 1 M glycerol solution?

A

6.02x10^23

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19
Q

When an ionic compound such as sodium chloride (NaCl) is placed in water, the component atoms of the NaCl crystal dissociate into individual sodium ions (Na+) and chloride ions (Cl-) In contrast, the atoms of covalently bonded molecules (e.g., glucose, sucrose, glycerol) do not generally dissociate when placed in aqueous solution. Which of the following solutions would be expected to contain the greatest number of solute particles (molecules or ions)?

A

1 L of 1.0 M NaCl

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20
Q

The molar mass of glucose is 180 g/mol. Which of the following procedures should you carry out to make a 1 M solution of glucose?

A

dissolve 180 g of glucose in 0.8 L of water, and then add more water until the total volume of the solution is 1 L

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21
Q

The molar mass of glucose (C6H12O6) is 180 g/mol. Which of the following procedures should you carry out to make a 0.5 M solution of glucose?

A

dissolve 90 g of glucose in a small volume of water, and then add more water until the total volume of the solution is 1 L

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22
Q

You have a freshly prepared 0.1 M solution of glucose in water. Each liter of this solution contains how many glucose molecules?

A

6.02x10^22

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23
Q

The molecular weight of water is 18 daltons. What is the molarity of 1 liter of pure water? (Hint: what is the mass of 1 liter of pure water?)

A

55.6 M

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24
Q

You have a freshly prepared 1 M solution of glucose in water. You carefully pour out a 100 mL sample of that solution. How many glucose molecules are included in that 100 mL sample?

A

6.02x10^22

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25
Q

A strong acid like HCl

A

ionizes completely in an aqueous solution

26
Q

Which of the following ionized completely in solution and is considered to be a strong base (alkali)?

A

NaOH

27
Q

A 0.01 M solution of a substance has a pH of 2. What can you conclude about this substance?

A

it is a strong acid that ionizes completely in water

28
Q

A given solution contains 0.0001 (10^-4) moles of hydrogen ions [H+] per liter. Which of the following best describes this solution?

A

acidic: will give H+ to weak acids, but accept H+ from strong acids

29
Q

A solution contains 0.0000001 (10^-7) moles of hydroxyl ions [OH-] per liter. Which of the following best describes this solution?

A

neutral

30
Q

What is the pH of a solution with a hydroxyl ion [OH-] concentration of 10^-12 M?

A

pH 2

31
Q

What is the pH of a 1 millimolar NaOH solution?

A

pH 11

32
Q

Which of the following solutions would require the greatest amount of base to be added to bring the solution to neutral pH?

A

gastric juice at pH 2

33
Q

What is the hydrogen ion [H+] concentration of a solution of pH 8?

A

10^-8 M

34
Q

if the pH of a solution is decreased from 9 to 8, it means that the

A

concentration of H+ has increased tenfold (10X) and the concentration of OH- has decreased to one-tenth (1/10) what they were at pH 9

35
Q

If the pH of a solution is increased from pH 5 to pH 7, it means that the

A

concentration of OH- is 100 times greater than what it was at pH 5

36
Q

One liter of a solution of pH 2 has how many more hydrogen ions (H+) than 1 L of a solution of pH 6?

A

10,000 times more

37
Q

One liter of a solution of pH 9 has how many more hydroxyl ions (OH-) than 1 L of a solution of pH 4?

A

100,000 times more

38
Q

Which of the following statements is true about buffer solutions?

A

they maintain a relatively constant pH when either acids or bases are added to them

39
Q

Buffers are substances that help resist shifts in pH by

A

both donating H+ to a solution when bases are added, and accepting H+ when acids are added

40
Q

One of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). Thus

H2CO3 HCO3- + H+

If the pH of the blood drops, one would expect

A

the HCO3- to act as a base and remove excess H+ with the formation of H2CO3

41
Q

One of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that, when placed in an aqueous solution, dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). Thus,

H2CO3 HCO3- + H+

If the pH of the blood increases, one would expect

A

a decrease in the concentration of H2CO3 and an increase in the concentration of HCO3-

42
Q

Assume that acid rain has lowered the pH of a particular lake to pH 4.0. What is the hydroxyl ion concentration of this lake?

A

1x10^-10 mol of hydroxyl ion per liter of lake water

43
Q

Research indicated that acid precipitation can damage living organisms by

A

washing away certain mineral ions that help buffer soil solution and are essential nutrients for plant growth

44
Q

Consider two solutions: solution X has a pH of 4; solution Y has a pH of 7. From this information, we can reasonably conclude that

A

the concentration of hydrogen ions in solution X is 1000 times as great as the concentration of hydrogen ions in solution Y

45
Q

If a solution has a pH of 7, this means that

A

the concentration of H+ ions in the water equals the concentration of OH- ions in the water

46
Q

Carbon dioxide (CO2) is readily soluble in water, according to the equation CO2 + H2O H2CO3. Carbonic acid (H2CO3) is a weak acid. Respiring cells release CO2 into the bloodstream. What will be the effect on pH of blood as that blood first comes in contact with respiring cells?

A

blood pH will decrease slightly

47
Q

A beaker contains 100 mL of NaOH solution at pH = 13. A technician carefully pours into the beaker 10 mL of HCl at pH = 1. Which of the following statements correctly describes the results of this mixing?

A

the pH of the beaker’s contents falls

48
Q

Equal volumes (5 mL) of vinegar from a freshly opened bottle are added to each of the following solutions. After complete mixing, which of the mixtures will have the highest pH?

A

100 mL of household cleanser containing 0.6 M ammonia

49
Q

Increased atmospheric CO2 concentrations might have what effect on seawater?

A

seawater will become more acidic, and carbonate concentrations will decrease

50
Q

How would acidification of seawater affect marine organisms?

A

acidification would decrease dissolved carbonate concentrations and hinder growth of corals and shell-building animals

51
Q

One idea to mitigate the effects of burning fossil fuels on atmospheric CO2 concentrations is to pipe liquid CO2 into the ocean at depths of 2500 feet or greater. At the high pressures at such depths, CO2 is heavier than water. What potential effects might result from implementing such a scheme?

A

both increased acidity of the deep waters and changed in the growth of bottom-dwelling organisms with calcium carbonate shells

52
Q

If the cytoplasm of a cell is at pH 7, and the mitochondrial matrix is at pH 8, this means that

A

the concentration of H+ ions is tenfold higher in the cytoplasm than in the mitochondrial matrix

53
Q

You have two beakers. One contains pure water, the other contains pure methanol (wood alcohol). The covalent bonds of methanol molecules are non polar, so there are no hydrogen bonds among methanol molecules. You pour crystals of table salt (NaCl) into each beaker. Predict what will happen

A

NaCl crystals will dissolve readily in water but will not dissolve in methanol

54
Q

You have two beakers. One contains a solution of HCl at pH 1.0. The other contains a solution of NaOH at pH=13. Into a third beaker, you slowly and cautiously pour 20 mL of the HCl and 20 mL of the NaOH. After complete stirring, the pH of the mixture will be

A

7.0

55
Q

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?

A

the absorption of heat by the breaking of hydrogen bonds

56
Q

The bonds that are broken when water vaporizes are

A

hydrogen bonds between water molecules

57
Q

Which of the following is a hydrophobic material?

A

wax

58
Q

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

A

number of molecules

59
Q

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

A

10^-4

60
Q

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

A

10^-10

61
Q

a slice of pizza has 500 kcal. If we could burn the pizza and use all the heat to warm a 50L 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.)

A

10 degrees C

62
Q

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.)

A

60g

Cambell Bio Ch 1 (6 decks)

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