Chemical Oceanography

Question 1

The only compound found on earth in large quantities in the liquid state
The only compound found on earth in all three states; solid, liquid, gas
All known life forms require water for their existence

Answer 1

Water

Question 2

Deep ditch or channel cut in the earth by running water after a prolonged downpour.

Answer 2

Gullies

Question 3

___ of earth covered with water
___ of the human body made up of water

Answer 3

70%, 67%

Question 4

A person can live a month without food, but only a __ without water.

Answer 4

Week

Question 5

Water Biological Importance:
1. (State the Equation)
2.

Answer 5

1. Photosynthesis CO2 + H20 = CH2O + O2
2. Transport dissolved and solid materials in living things

Question 6

As water cycles around, it undergoes chemical reactions with atmospheric gases, rocks, plants, and other substances = ___?

Answer 6

Hydrological Cycle, Change in Water Composition

Question 7

Properties of Water:
1.
2.
3.
4.
5.
6.
7.

Answer 7

1. Maximum density at 4deg C
2. High heat capacity
3. High melting temperature
4. High boiling point
5. High heat of vaporization
6. High surface tension
7. Universal solvent

Question 8

• Reason why liquid water is unusual lies in the way the molecules of liquid water associate with one another to form an ordered structure
• There is a relationship between ____ and its properties

Answer 8

Water Structure

Question 9

Tetrahedal angle is ___, in water angle is ___. Water molecules are asymmetrical is shape with the two hydrogen molecules at one end, separated by ___ when in the gaseous or liquid phase and ___ when ice.

Answer 9

109.5, 104.5, 105 degrees, 109.5 degrees

Question 10

H atoms joined to the O by 2 _____.
Has + end (H) and - end (O) = _____ or ____

Answer 10

Covalent Bonds, Charge Distortion, Dipole

Question 11

• Because water molecules act as dipole, it forms H bonds with other molecules
• +ly charged H atom of 1 water molecule attracted to unshared, negatively charged e pair in another water molecule to form H bonds
• ___ gives water its unusual qualities
• H bonds constantly form and break

Answer 11

Hydrogen Bonding / H Bonding

Question 12

• Due to this, water forms a perfect tetrahedron (109.5 deg)
• Expands due to need for more room to hold the crystal in place (mean volume increases)
• Volume ____, Density ____, hence ice is lighter, it FLOATS

Answer 12

Density, Increases, Decreases

Question 13

Water ____ as it freezes.
Volume increases hence density decreases (D=mass/vol); ice ____.

Answer 13

Expands, Floats

Question 14

Density = ___?
Solid State: Volume ___, Density ___
Liquid State: Volume ___, Density ___
Gaseous State: Volume ___, Density ___

Answer 14

Mass
Increase, Decrease
Decrease, Increase
Decrease, Increase

Question 15

Maximum Density at ?

Answer 15

4 Degree Celsius

Question 16

Application of Density:
1. Also Called ____?
2.

Answer 16

1. Density characteristics important for freshwater lakes in mid latitudes, Spring overturn
2. Expansion of water important in the physical weathering of rocks

Question 17

Freezing Point = _____: ___?
Boiling Point= ____: ___?

Answer 17

Melting Point, 0 Celsius
Condensation Point, 100 Celsius

Question 18

Boiling Point Equation:
- water different, boils at 100oC instead of -80oC - due to ___ (acts to hold molecule in place)
- charge distortion ___ between H and O than H and S
- hence H2O liquid at room temp, H2S gas at room temp

Answer 18

H2O > H2Te > H2Se > H2S, H Bonds, Highest

Question 19

High Boiling and Melting Point Application:
1.

Answer 19

• Permits water to exist as liquid in the earth’s surface

Question 20

• amount of heat required to raise the temp of substance by 1oC (Unit: cal/oC/g)
  
  • water has high ___, a lot of energy needed to break ___ before there is an increase in temp
• Heat Capacity per unit mass?

Answer 20

Heat Capacity, H Bonds, Specific Heat

Question 21

Water has the ___ heat capacity of any common liquid or solid at ___?

Answer 21

Highest, 1 Cal/Celsius

Question 22

Application of High Heat Capacity:
*
*

Answer 22

• Helps moderate climate (buffer for climate change)
• Keeps the equator bearable

Question 23

Water has high ____:
- Heat that is absorbed or release during change of state
- Heat that cause a change in state with no change in temperature

Answer 23

Latent Heat

Question 24

When an object is heated, its temperature rises as heat is added. The increase in heat is called ____? Similarly, when heat is removed from an object and its temperature falls, the heat removed is also called ____? Heat that causes a change in temperature in an object is called ____?

Answer 24

Sensible Heat

Question 25

Application of Heat of Vaporization: * * *

Answer 25

- heat transfer, drives the water cycle - liquid water absorbs heat at one place and evaporates, then it is transported to another place where it is cooled and condenses - evaporation dissipates much of heat of solar radiation thus moderating surface temp

Question 26

Global Thermostatic Effects: /- /-

Answer 26

- Water's properties moderate temperature on Earth's Surface - Heat energy exchanged in evaporation-condnesation cycle.

Question 27

Why Coastal Climates have mild Climates? - In summer, water evaporates from the surfaces of oceans and takes heat energy from the surrounding land 🡪 __. - In winter, water vapor condenses and releases heat to the surrounding 🡪 ___.

Answer 27

- The nearby land mass is cooled - Temperature of the surrounding air is raised.

Question 28

- measure of how strongly molecules of liquid are attracted to each other across an interphase - water has high ___ - water molecules at surface attracted to molecules below them by ___

Answer 28

Surface Tension, H Bonds

Question 29

A ______ forms as hydrogen bonds form a strong attraction between the top layer of water molecules and the underlying molecules.

Answer 29

Surface Tension Layer

Question 30

____ can walk on because of the surface tension of the water.

Answer 30

Water Striders

Question 31

___ are the result of wind travelling over water. The ___ arise from the surface tension of water.

Answer 31

Waves

Question 32

Application of High Surface Tension: * * *

Answer 32

- causes sea surface to become rougher - makes it easier to transfer wind energy to the sea - friction between wind and water responsible for generation of large waves and for major circulation of upper ocean

Question 33

- water transparent to visible light

Answer 33

Absorption of Radiation

Question 34

Application of Absorption of Radiation *

Answer 34

- necessary for photosynthesis (up to 100m depth in clear waters)

Question 35

____ entering the ocean through the sea surface is quickly attenuated such that by ___ 99% of the energy has been absorbed. This has consequences for the heating of the ocean by solar radiation; the heating and photosynthesis is confined to the ____.

Answer 35

Shortwave Radiation, 100m, Surface Layers

Question 36

- excellent solvent for ionic salts and polar molecules because of dipolar nature

Answer 36

Water as Solvent

Question 37

Application of Water as Solvent: *

Answer 37

- important in transfer of dissolved substances in hydrological cycle and in biological systems

Question 38

Water molecules stick to other ____. ____ produces ionic bond. ____: Water can dissolve almost anything

Answer 38

Polar Molecules, Electrostatic Attraction, Universal Solvent

Question 39

Effect of Salt on the Properties of Water 1. Boiling point - ____ - because electrical interactions of ions increase the energy required to remove water molecules from solution increases 2. Freezing Point - ____ - Because more energy removed before water molecules transferred from liquid to solid 3. Density - ___ (Dseawater = ___?) - Interactions of salt ions disrupts normal water structure and increase packing density of molecules

Answer 39

Increase, Decrease, Increase (Dseawater = 1.025 g/mol)

Question 40

Water vapor in Earth’s early atmosphere reacted with volcanic gases and dust; most important gases: ____, ____, ___, – formed acids (___, ___, ___) in rain water, which dissolved minerals from rocks. When it rains on land, some of the water dissolves minerals like salt, in rocks. The water flows in rivers to the sea carrying the minerals. When water evaporates back out of the ocean, it leaves the minerals behind. The ___ make seawater salty.

Answer 40

Chlorine, Carbon Dioxide, Sulfur Dioxide HCl, H2SO4, H2CO3 Minerals

Question 41

Gain of dissolved material and loss of precipitates; both high-temperature reactions at mid-ocean ridges & low temperature reactions with volcanic rocks and sediments.

Answer 41

Water / Sediment interaction at seafloor

Question 42

Measure of the total dissolved salts in seawater: - = salt/kg seawater - Are the major ions = ___: ___ = ___ major ions? - Particulate: ___? ____ make a significant contribution to salinity.

Answer 42

Salinity Dissolved, <0.45 picometer = 99% >0.45 picometer Major Ions

Question 43

Salinity of Seawater: ____ or ____ or ____

Answer 43

35 ppt, 35% degree Celsius, 3.5%

Question 44

Salinity Range: 33-37 ppt: ____ <25 ppt: ____ >40 ppt: ____ 0 ppt: ____

Answer 44

Seawater, Brackish Water, Hypersaline Water, Freshwater

Question 45

Major ions that make up Salinity in Cations and their measurements: 1. 2. 3. 4. 5.

Answer 45

1. Sodium (Na) - 468 mM 2. Magnesium (Mg) - 53.2 mM 3. Calcium (Ca) - 10.2 mM 4. Potassium (K) - 10.2 mM 5. Strontium (Sr) - 0.09 mM

Question 46

Major ions that make up salinity in Anions and their measurements: 1. 2. 3. 4. 5.

Answer 46

1. Chloride (Cl) - 545 mM 2. Sulfate (SO4) - 28.8 mM 3. Bicarbonate (HCO3) - 2.4 mM 4. Bromide (Br) - 0.8 mM 5. Boron (B) - 0.4 mM

Question 47

Ions in terms of abundance: 1. 2. 3. 4. 5.

Answer 47

1. Chloride - 545 mM - 55% 2. Sodium - 468 mM - 32% 3. Sulfate - 28.8 mM - 8% 4. Magnesium - 53.2 mM - 4% 5. Potassium - 10.2 mM - ~1%

Question 48

Measurement of Salinity - evaporate water to dryness and weigh salt residue * tedious and time consuming, not accurate because some salts can evaporate with water - AgNO3 + NaCl = AgCl (precipitate) and calculate salinity Sal = 1.805 Cl * accurate but tedious and costly (reagents) - seawater conducts current due to ions present * use CTD (Conductivity-Temp-Depth) profiler - light bends (refracts) as it passes from one medium to another (air to water) - refraction of light will change with change in salinity * not sensitive method, only rough estimate

Answer 48

- Direct Method - Measure Chlorinity with AgNO3 - Conductivity - Refractometer

Question 49

- compare conductivity of seawater sample to conductivity of a standard seawater solution -> ___ - Tables are available for the conversion of the___ to salinity - since ___ is obtained, units cancel out; hence salinity now in ‘___’ or ___ - uses ____ * accurate and easy

Answer 49

RATIO, Practical Salinity Unit, PSU, Salinometer

Question 50

- Absolute amount of salt in seawater varies, but the relative proportions of the major ions is constant - Ratio of the major ions is the same at any salinity Na/Cl = 0.85 Ca/SO4 = 0.35 Exceptions: ___, ___

Answer 50

Constancy of Composition CaCO3 dut to being involved in biological cycle, SO4 in anoxic systems

Question 51

As seawater evaporates - ___ soluble salts reach ___ first

Answer 51

Least, Saturation

Question 52

- sequence of precipitation is in the order of increasing solubility 1. 2. 3. 4. 5. 6. 7.

Answer 52

1. CaCO3 = least soluble 2. CaSO4 3. NaCl 4. MgSO4 5. MgCl2 6. NaBr 7. KBr = most soluble

Question 53

Processes affecting Salinity: - Adding freshwater to ocean - ___? * Runoff, melting icebergs, precipitation - Removing water from ocean - ___? * Sea ice formation, Evaporation

Answer 53

Decreasing Salinity, Increasing Salinity

Question 54

Density of sea water is a function of ___, ___, and ___.

Answer 54

Density, Salinity, Pressure

Question 55

Colder water is ____. Saltier water is ____. High pressure ____ density. The dependence is nonlinear. δt = (ρ-1)103 ρ is the ___?

Answer 55

Denser, Denser, Increases, Density