Test Bank Ch.5 The Chemistry Of Seawater

Investigating Oceanography, 3e (Sverdrup)

Chapter 5 The Chemistry of Seawater

1) The polar nature of water molecules aids in water's solvent abilities.

2) The relative molar abundance of carbon, nitrogen, and phosphorus in marine phytoplankton can be expressed in a relationship called the ________ ratio.

3) The salinity of a water sample can be determined by multiplying its ________ by 1.80655.

4) An ion with a positive charge is called a(n) ________

5) Identify the four seawater constituents that are present in the highest concentration.

A) magnesium

B) bromide

C) sodium

D) chloride

E) calcium

F) potassium

G) sulfate

6) The dissolving ability of water is related to ________.

A) the attraction between the water molecule's positive and negative charges and charges on other atoms

B) its ability to form hydrogen bonds with other molecules

C) its ability to transmit energy from water molecule to water molecule

D) the attraction between the water molecule's positive and negative charges and charges on other atoms and its ability to form hydrogen bonds with other molecules

E) the attraction between the water molecule's positive and negative charges and charges on other atoms, its ability to form hydrogen bonds with other molecules, and its ability to transmit energy from water molecule to water molecule

7) Salinity of seawater is approximately equal to the total dissolved salts in seawater expressed as grams of salt per kilogram of seawater.

8) The chemical constituents of sea salt that are not utilized or altered by biological processes are called nonconservative.

9) Nutrients and dissolved gases in seawater are considered conservative substances.

10) Seawater percolating through the fractured crust along ridge systems acts to both remove salts from and add salts to seawater.

11) Formation of evaporites acts to add salts to seawater.

12) The rule of constancy of composition of sea salts for open-ocean water specifies that regardless of the salinity, the major ions always appear in the same ratio to each other.

13) When the salinity of a seawater sample changes, the ratio of the major salt ions does not change.

14) Instruments used to measure the electrical conductivity of seawater can produce continuous readings of salinity with depth or continuous readings of salinity with time at a fixed depth.

15) Cold seawater holds less oxygen than warm seawater at the same pressure and salinity.

16) Anoxic water contains too much oxygen.

17) More oxygen is found in surface waters at lower latitudes than in surface waters at polar latitudes.

18) Carbon dioxide concentrations in seawater increase with depth.

19) In the process called osmosis, water naturally travels through a semipermeable membrane from the side of low salt concentration to the side of high salt concentration.

20) The process of reverse osmosis uses pressure to separate fresh water from salt water through a semipermeable membrane.

21) The oceans are a major contributor of oxygen to the earth's atmosphere.

22) When salt-forming ions are placed in water, they combine with each other and form solids.

23) Acid rain falling on seawater has little effect on the pH of the oceans.

24) An ion with a negative charge is a cation.

25) The saturation value of oxygen in seawater increases as the temperature increases.

26) Surface values of dissolved oxygen may exceed 100% saturation.

27) An ion with a positive charge is known as a cation.

28) Surface salinities at high latitudes tend to be greater in summer than winter.

29) The proportions of the major salts in seawater are constantly changing.

30) The percentage of oxygen dissolved in seawater is greater in surface waters than in the deep ocean.

31) If the salinity of ocean water is 36‰, there are ________ g of salt left from evaporating 2 kg of seawater.

A) 9

B) 18

C) 36

D) 54

E) 72

32) The average salinity of the oceans is about ________ parts per thousand (‰).

A) 30

B) 35

C) 37

D) 40

E) 45

33) Sources of the oceans' salts are believed to include ________.

A) Earth's crust

B) Earth's early atmosphere

C) volcanic eruptions

D) Earth's crust and Earth's early atmosphere

E) Earth's crust, Earth's early atmosphere, and volcanic eruptions

34) Ions are removed from seawater most effectively by ________.

A) evaporation

B) freezing

C) adsorption

D) bacterial action

E) None of these is correct; one method is not more effective than another.

35) If a chemical is not very abundant in the ocean but has a high rate of delivery to the ocean from land sources, it will have a ________ residence time in the ocean and will ________ become part of the seafloor sediments.

A) long; quickly

B) long; slowly

C) short; quickly

D) short; slowly

E) variable; variably

36) Which situations cause an ion to have a long residence time in the oceans?

A) A high rate of ion addition

B) A rapid rate of reaction with other substances

C) Small total amount of ion present

D) A high rate of ion addition and a rapid rate of reaction with other substances acting together

E) None of these is correct.

37) The major ionic constituents of sea salt are normally found to ________.

A) have a constant ratio of each constituent to each other

B) behave as conservative materials

C) have the same ratio to each other even when diluted by rainwater

D) All of these are correct.

E) None of these is correct.

38) Dittmar analyzed approximately seventy seawater samples collected around the world during the Challenger Expedition. He concluded that ________.

A) seawater had the same salinity worldwide

B) salt content changes due to processes that add or subtract salt

C) the major ions were always present in the same ratios

D) dissolved gases are always present in the same ratios

E) the major ions were always present in the same ratios and dissolved gases are always present in the same ratios

39) Salinity may be measured by checking the water's ________.

A) viscosity

B) temperature

C) conductivity

D) pressure

E) surface tension

40) Electrical conductivity readings at a known temperature measure ________.

A) salinity

B) temperature

C) pressure

D) viscosity

E) density

41) Sources of oxygen in the open sea include ________.

A) the atmosphere

B) photosynthesis

C) respiration and decay

D) the atmosphere and photosynthesis

E) photosynthesis and respiration and decay

42) The depth at which the rate of photosynthesis balances the rate of plant respiration is known as the ________.

A) saturation value depth

B) compensation depth

C) gas equilibrium depth

D) photosynthesis cutoff depth

E) None of these is correct.

43) Carbon dioxide in seawater keeps the water's pH ________.

A) slightly alkaline

B) strongly alkaline

C) slightly acid

D) strongly acid

E) neutral

44) The pH of seawater is regulated by its ________.

A) carbon dioxide concentration

B) oxygen

C) temperature

D) pressure

45) Which of these processes results in the transfer of the carbon from carbon dioxide to the deep sea?

A) Photosynthesis

B) Respiration

C) Decay

D) Photosynthesis and decay

E) Photosynthesis, respiration, and decay

46) Which of the following chemicals is commercially extracted from seawater?

A) Sulfur

B) Gold

C) Manganese

D) Bromine

E) Phosphate

47) A device used to separate fresh water from salt water using heat is called a(n) ________.

A) osmometer

B) dialysis machine

C) still

D) ion exchange column

E) salt fountain

48) Electrodialysis produces ________ from low-salinity seawater.

A) bromine and magnesium

B) energy

C) fresh water

D) oxygen and carbon dioxide

E) table salt (sodium chloride)

49) The concentration of carbon dioxide in surface water is low, whereas the concentration of oxygen is high because of the ________.

A) difference in solubility of the gases

B) exchange of gases between the atmosphere and the ocean

C) photosynthesis process

D) respiration of plants and animals

E) conversion of carbon dioxide to bicarbonate

50) The total change in concentration of carbon dioxide with depth is small because ________.

A) carbon dioxide combines with water to form carbonic acid and bicarbonate

B) decay occurs at all depths

C) photosynthesis occurs only at the surface

D) carbon dioxide is added directly from the atmosphere

E) carbon dioxide reacts with oxygen

51) Trace elements in seawater are ________.

A) toxic to marine life forms

B) necessary for many marine life forms

C) found in concentrations suitable for commercial use

D) significant components of the total salt content of seawater

E) in higher concentrations at lower salinities

52) The residence time of an ion in the oceans may be determined by ________.

A) multiplying the input rate by the output rate

B) multiplying the total amount of the ion by either the input or output rate

C) dividing the total amount of the ion by either the input or output rate

D) dividing the ionic concentration by the input or output rate

E) multiplying the ionic concentration by the total amount of the ion

53) Which ion has the shortest residence time in the oceans?

A) Chloride

B) Sodium

C) Potassium

D) Sulfate

E) Iron

54) Seawater taken from an area with a large, growing plant population has a ________.

A) low CO2 and high nutrient content

B) low O2 and low nutrient content

C) high O2 and low nutrient content

D) high O2 and high CO2 content

E) None of these is correct.

55) Nutrients are nonconservative constituents of seawater because they ________.

A) maintain constant ratios to each other

B) do not maintain constant ratios to each other

C) are recycled into plants and animals

D) maintain constant ratios to each other and are recycled into plants and animals

E) do not maintain constant ratios to each other and are recycled into plants and animals

56) The rate at which the oceans absorb carbon dioxide is controlled by ________.

A) temperature, salinity and pressure

B) pH

C) mixing and circulation processes

D) temperature, salinity and pressure, pH, and mixing and circulation processes

57) Which desalination process requires the least energy?

A) Reverse osmosis

B) Distillation

C) Ion exchange

D) Freezing

E) Electrodialysis

58) Which latitudinal area tends to have the highest average surface salinity?

A) Polar areas (80° to 90°)

B) Equatorial areas (0° to 10°)

C) Tropics (25° to 30°)

D) Midlatitudes (60°)

E) None of these is correct.

59) Which of the following ions has the highest concentration in seawater?

A) Na+

B) Cl–

C) Mg2+

D) K+

E) Ca2+

60) Which gas has the highest concentration throughout the entire ocean?

A) Oxygen

B) Carbon dioxide

C) Nitrogen

D) Argon

E) Concentrations vary with time.

61) Sea surface salinity is a function of ________ and ________.

62) The process of adherence of ions and molecules onto a particle's surface is called ________.

63) Check each of the following constituents of seawater that are conservative constituents.

A) Sodium

B) Oxygen

C) Sulfate

D) Carbon dioxide

E) Phosphorus

F) Chloride

64) The residence time of iron and sodium in the oceans is approximately the same.

65) Profiles of the concentration of oxygen and carbon dioxide in seawater from the surface to a depth of about 800 m are mirror images of each other.

66) The depth at which the rate of photosynthesis balances the rate of respiration is called the ________ depth.

67) The ratio of chlorine to sodium in seawater is about 1.8.

68) In order to change the pH of water by one integer number (from 7 to 8 or from 8 to 7, for instance), you would have to change the concentration of the hydrogen ion by a factor of ________.

A) 1000

B) 500

C) 100

D) 50

E) 10

69) Carbon dioxide is added to seawater by ________.

A) photosynthesis

B) respiration

C) decomposition

D) transfer from the atmosphere

E) respiration, decomposition and transfer from the atmosphere

70) Which of the following is NOT a major dissolved constituent of seawater?

A) Iron

B) Chloride

C) Sodium

D) Magnesium

E) Potassium

71) An average value for the salinity of seawater could be (pick the best choice).

A) 15 g/kg

B) 20 g/kg

C) 25 g/kg

D) 30 g/kg

E) 35 g/kg

72) The major ions of seawater are those which ________.

A) are used by living organisms to build their soft tissues

B) have residence times that are short relative to the mixing time of the oceans

C) do not vary from place to place in the oceans, except as salinity varies

D) None of these is correct

E) All of these are correct

73) Major ions constitute ________.

A) 100% of all ions in seawater

B) 99.3% of all ions in seawater

C) 95.3% of all ions in seawater

D) 91.3% of all ions in seawater

E) 50% of all ions in seawater

74) The salinity of surface waters in the oceans ________.

A) varies mainly in response to the balance between evaporation and precipitation at a given locality

B) varies mainly in response to the intensity of winds at a given locality

C) varies mainly in response to variations in the depth of the euphotic layer

D) is everywhere the same

E) varies chaotically

75) As we go below the euphotic zone of the open ocean and into greater depths, ________.

A) oxygen increases with depth

B) carbon dioxide increases with depth

C) photosynthesis increases with depth

D) respiration decreases with depth

E) None of these is correct

76) Oxygen (O2) ________.

A) is not affected by photosynthesis

B) is typically found in the lowest concentrations where photosynthesis takes place

C) is of no use whatsoever to any organism in the euphotic zone

D) All of these are correct

E) None of these is correct

77) The balance between photosynthesis and respiration in the open ocean's water column ________.

A) changes with depth

B) favors photosynthesis for most of the euphotic zone

C) is affected by light availability

D) All of these are correct.

E) None of these is correct.

78) The biological pump ________.

A) refers to the heaving and hoeing of whales

B) removes particles from the surface ocean to greater depths

C) removes the majority of particles generated in the surface ocean through photosynthesis

D) All of these are correct.

E) None of these is correct.

79) The Redfield ratio ________.

A) is related to the average composition of all plankton in the ocean

B) was originally formulated to relate carbon, oxygen, and hydrogen

C) is of no practical importance to oceanography today

D) All of these are correct.

E) None of these is correct.

80) An ion with a negative charge is called a(n) ________.