Chemical Oceanography Flashcards
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
Water
Deep ditch or channel cut in the earth by running water after a prolonged downpour.
Gullies
___ of earth covered with water
___ of the human body made up of water
70%, 67%
A person can live a month without food, but only a __ without water.
Week
Water Biological Importance:
1. (State the Equation)
2.
- Photosynthesis CO2 + H20 = CH2O + O2
- Transport dissolved and solid materials in living things
As water cycles around, it undergoes chemical reactions with atmospheric gases, rocks, plants, and other substances = ___?
Hydrological Cycle, Change in Water Composition
Properties of Water:
1.
2.
3.
4.
5.
6.
7.
- Maximum density at 4deg C
- High heat capacity
- High melting temperature
- High boiling point
- High heat of vaporization
- High surface tension
- Universal solvent
- 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
Water Structure
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.
109.5, 104.5, 105 degrees, 109.5 degrees
H atoms joined to the O by 2 _____.
Has + end (H) and - end (O) = _____ or ____
Covalent Bonds, Charge Distortion, Dipole
- 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
Hydrogen Bonding / H Bonding
- 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
Density, Increases, Decreases
Water ____ as it freezes.
Volume increases hence density decreases (D=mass/vol); ice ____.
Expands, Floats
Density = ___?
Solid State: Volume ___, Density ___
Liquid State: Volume ___, Density ___
Gaseous State: Volume ___, Density ___
Mass
Increase, Decrease
Decrease, Increase
Decrease, Increase
Maximum Density at ?
4 Degree Celsius
Application of Density:
1. Also Called ____?
2.
- Density characteristics important for freshwater lakes in mid latitudes, Spring overturn
- Expansion of water important in the physical weathering of rocks
Freezing Point = _____: ___?
Boiling Point= ____: ___?
Melting Point, 0 Celsius
Condensation Point, 100 Celsius
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
H2O > H2Te > H2Se > H2S, H Bonds, Highest
High Boiling and Melting Point Application:
1.
- Permits water to exist as liquid in the earth’s surface
- 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?
Heat Capacity, H Bonds, Specific Heat
Water has the ___ heat capacity of any common liquid or solid at ___?
Highest, 1 Cal/Celsius
Application of High Heat Capacity:
*
*
- Helps moderate climate (buffer for climate change)
- Keeps the equator bearable
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
Latent Heat
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 ____?
Sensible Heat
Application of Heat of Vaporization:
*
*
*
- 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
Global Thermostatic Effects:
/-
/-
- Water’s properties moderate temperature on Earth’s Surface
- Heat energy exchanged in evaporation-condnesation cycle.
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 🡪 ___.
- The nearby land mass is cooled
- Temperature of the surrounding air is raised.
- 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 ___
Surface Tension, H Bonds
A ______ forms as hydrogen bonds form a strong attraction between the top layer of water molecules and the underlying molecules.
Surface Tension Layer
____ can walk on because of the surface tension of the water.
Water Striders
___ are the result of wind travelling over water. The ___ arise from the surface tension of water.
Waves
Application of High Surface Tension:
*
*
*
- 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
- water transparent to visible light
Absorption of Radiation
Application of Absorption of Radiation
*
- necessary for photosynthesis (up to 100m depth in clear waters)
____ 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 ____.
Shortwave Radiation, 100m, Surface Layers
- excellent solvent for ionic salts and polar molecules because of dipolar nature
Water as Solvent
Application of Water as Solvent:
*
- important in transfer of dissolved substances in hydrological cycle and in biological systems
Water molecules stick to other ____.
____ produces ionic bond.
____: Water can dissolve almost anything
Polar Molecules, Electrostatic Attraction, Universal Solvent
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
Increase, Decrease, Increase (Dseawater = 1.025 g/mol)
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.
Chlorine, Carbon Dioxide, Sulfur Dioxide
HCl, H2SO4, H2CO3
Minerals
Gain of dissolved material and loss of precipitates; both high-temperature reactions at mid-ocean ridges & low temperature reactions with volcanic rocks and sediments.
Water / Sediment interaction at seafloor
Measure of the total dissolved salts in seawater:
- = salt/kg seawater
- Are the major ions = ___: ___ = ___ major ions?
- Particulate: ___?
____ make a significant contribution to salinity.
Salinity
Dissolved, <0.45 picometer = 99%
>0.45 picometer
Major Ions
Salinity of Seawater: ____ or ____ or ____
35 ppt, 35% degree Celsius, 3.5%
Salinity Range:
33-37 ppt: ____
<25 ppt: ____
>40 ppt: ____
0 ppt: ____
Seawater, Brackish Water, Hypersaline Water, Freshwater
Major ions that make up Salinity in Cations and their measurements:
1.
2.
3.
4.
5.
- Sodium (Na) - 468 mM
- Magnesium (Mg) - 53.2 mM
- Calcium (Ca) - 10.2 mM
- Potassium (K) - 10.2 mM
- Strontium (Sr) - 0.09 mM
Major ions that make up salinity in Anions and their measurements:
1.
2.
3.
4.
5.
- Chloride (Cl) - 545 mM
- Sulfate (SO4) - 28.8 mM
- Bicarbonate (HCO3) - 2.4 mM
- Bromide (Br) - 0.8 mM
- Boron (B) - 0.4 mM
Ions in terms of abundance:
1.
2.
3.
4.
5.
- Chloride - 545 mM - 55%
- Sodium - 468 mM - 32%
- Sulfate - 28.8 mM - 8%
- Magnesium - 53.2 mM - 4%
- Potassium - 10.2 mM - ~1%
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)
- accurate but tedious
- 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
- Direct Method
- Measure Chlorinity with AgNO3
- Conductivity
- Refractometer
- 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
RATIO, Practical Salinity Unit, PSU, Salinometer
- 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: ___, ___
Constancy of Composition
CaCO3 dut to being involved in biological cycle, SO4 in anoxic systems
As seawater evaporates
- ___ soluble salts reach ___ first
Least, Saturation
- sequence of precipitation is in the order of increasing solubility
1.
2.
3.
4.
5.
6.
7.
- CaCO3 = least soluble
- CaSO4
- NaCl
- MgSO4
- MgCl2
- NaBr
- KBr = most soluble
Processes affecting Salinity:
- Adding freshwater to ocean - ___?
* Runoff, melting icebergs, precipitation
- Removing water from ocean - ___?
* Sea ice formation, Evaporation
Decreasing Salinity, Increasing Salinity
Density of sea water is a function of
___, ___, and ___.
Density, Salinity, Pressure
Colder water is ____.
Saltier water is ____.
High pressure ____ density.
The dependence is nonlinear.
δt = (ρ-1)103
ρ is the ___?
Denser, Denser, Increases, Density
