OCE 5
Why is there low surface salinity in the high latitudes, and why is there higher surface salinity in the low latitudes?
Temperature is low in high latitude and high in low latitudes.
Describe the relationship between solubility, temperature, pressure, and the concentration of gases in seawater.
Solubility in seawater, pressure and temperature of seawater control the concentrations of Carbon and Oxygen in the ocean. CO2 is highly soluble and readily reacting with water to form other inorganic compounds.
In the open ocean, average seawater salinity is ___________.
35‰
What accounts for all of the unique properties of water?
The water molecule's unique geometry causes it to have a resulting electrical polarity
Describe the pycnocline, including where it occurs in the ocean.
A layer of rapidly changing density, occurring in low-density upper water of the Ocean but also in swimming pools, ponds and lakes.
Describe the halocline, including where it occurs in the ocean.
A layer of rapidly changing salinity and it occurs in both high and low latitude regions.
Describe the thermocline, including where it occurs in the ocean.
A layer of rapidly changing temperature occurring in low-density upper water of the Ocean but also in swimming pools, ponds, and lakes.
Explain the difference between an acidic substance and an alkaline (basic) substance.
Acidic substances release hydrogen ions when dissolved in water. Base substances release hydroxide ions when dissolved in water. When substances dissociate in water, they make the solution more acidic or basic.
Why are the freezing and boiling points of water higher than would be expected for a compound of its molecular makeup?
Because additional heat energy is required to overcome its hydrogen bonds and van der Waals forces, due to the unusual bend (geometry) of the water molecule (hydrogen atoms do not form on opposite sides of oxygen atom-linear 180-degree shape, but rather at a 105-degree angle making it look like a pyramid) and resulting polarity
What condition of salinity makes it possible to determine the total salinity of ocean water by measuring the concentration of only one constituent, the chloride ion?
Because seawater has constancy of composition, and the chloride ion occurs in the greatest abundance and is the easiest to measure accurately.
Describe the two main methods of seawater desalination.
DISILLATION where saltwater is boiled then the water vapor cooled where it condenses and is collected as freshwater. REVERSE OSMOSIS: water on the salty side is highly pressurized to drive water molecules, not salt and other membranes, to the freshwater.
As water cools, two distinct yet seemingly contradictory changes take place in the behavior of water molecules: (1) Their slower movement causes water density to increase and (2) the formation of bulky ice crystals causes water density to decrease. Describe how the combination of these two factors causes pure water to experience its maximum density at 4 C (39.2 F).
Density is mass per unit volume or how heavy something is for its size. Based on how tightly the molecules are packed together determines its density. Pure water has a density of 1.0g/cm. This density is met only when water reaches its freezing point at 4 C (39 F) because the increase and decrease in density occurring at the same time balance perfectly. The thermal motion decreases so water molecules occupy less volume.
Why is the underlying reason that seawater desalination is so expensive?
Desalination is expensive because it requires large amounts of heat energy to boil the saltwater.
Why would global warming cause the ocean to absorb less CO2? What about O2?
Due to human-caused industrial processes pumping CO2 into the atmosphere, ends up in the ocean called carbon sink. With rising temperatures, the oceans warm, the solubility of carbon dioxide in seawater decreases and saturates seawater with CO2. The atmosphere will hold more CO2 which increases the amount of atmospheric global warming. Since 1960 O2 levels have declined in the oceans. Concerns are that oceans may suffer from a low oxygen condition called HYPOXIA, causing impacts on marine life devastating for fisheries and coastal economies.
Describe how excess heat energy absorbed by Earth's low-latitude regions is transferred to heat-deficient higher latitudes through a process that uses water's latent heat of evaporation.
EVAPORATION is the conversion of a liquid to a gas below the boiling point. Latent heats of vaporization and condensation are identical. Through the evaporation-condensation cycle life is made possible on Earth as huge amounts of heat energy are exchanged. The process: Sun radiates energy to Earth and some is stored in the oceans as heat. Evaporation removes this heat energy from oceans and carries high into the atmosphere. In the cooler upper atmosphere, water vapor condenses into cloud (which source precipitation like rain and snow). The formation of clouds causes water's latent heat of condensation to be released back to the atmosphere. Evaporation-Condensation cycle removes huge amounts of heat energy from the low-latitude oceans and adds huge amounts of heat energy to heat-deficient higher latitudes and heat released when sea ice forms moderates Earth's high-latitude regions near the poles.
Using everyday language, explain why ice is less dense than liquid water. From a chemical standpoint, why is this so unusual?
Expansion and contraction of water molecules help explain. As water gets to its freezing point of 4 C or 39 F, the temperature decreases while the density increases due to thermal motion decreasing. The water molecules occupy less volume. Below 4 C or 39 F, volume increases again because water molecules line up to form ice crystals with the water molecules widely spaced. Water stops contracting and actually expands.
In the high latitudes, there is a prominent and well-developed thermocline
FALSE
The heat capacity of water is lower than that of most other substances.
FALSE
How does hydrogen bonding produce the surface tension phenomenon of water?
Hydrogen bonds between water molecules are much weaker than the covalent bonds that hold the hydrogen and oxygen atoms of water molecules together, so weaker hydrogen bonds from between adjacent water molecules and stronger bonds occur within water molecules.
Why is the latent heat of vaporization so much greater than the latent heat of melting
In order to reach the latent heat of vaporization, 540 calories per gram for water must be present and represents the amount of heat that must be added to 1 gram of substance at its boiling point to break intermolecular bonds and complete the change of state from liquid to vapor (gas). To melt or go from solid to liquid, just enough hydrogen bonds must be broken to allow water molecules to slide past one another. To vaporize or go from liquid to gas, ALL of the hydrogen bonds must be completely broken so that individual water molecules can move about freely.
What physical conditions create brackish water in the Baltic Sea and hypersaline water in the Red Sea?
In the Baltic Sea, salinity averages 10 0/00, conditions that create brackish water are freshwater from rivers and high rainfall and seawater mix. In the Red Sea, salinity averages 42 0/00 due to hypersaline when seas and inland bodies of water experience high evaporation rates and limited open-ocean circulation.
Thermocline
In water, a distinctive temperature transition zone that separates an upper layer that is mixed by wind (the epilimnion) and a colder, deep layer that is not mixed (the hypolimnion)
KINETIC ENERGY
Means moving. Heat can be changed by combustion, chemical reactions, friction or radioactivity. Example: Water can exist in solid liquid or gas depending on the amount of heat added.
Explain the difference between organic and inorganic carbon and describe a reaction associated with each.
Organic carbon is found in tissues of living creatures, inorganic carbon is found in shells of marine organisms . Inorganic carbon is at the ocean's surface when atmospheric CO2 dissolves in seawater. It reacts with water to form carbonic acid, enters the carbonate buffering system & contributes to form of calcium carbonate shells of marine organisms. Biocarbonate is the most abundant form of dissolved inorganic carbon in the ocean It is also taken in by marine plants and algae in production of organic compounds during photosynthesis.
Describe the ways in which dissolved components are added and removed from seawater.
Precipitation, RUNOFF (steam discharge), melting icebergs and melting sea ice decrease seawater salinity by adding more freshwater. The formation of sea ice and evaporation increase seawater salinity by removing water from the ocean. They include stream runoff (streams dissolve ions from continental rocks & carry them to the sea and volcanic eruptions both on land and on the sea floor, atmosphere contributing gasses and biological interactions.
How does the ocean's buffering system work?
Reactions involving carbonate chemicals serve to buffer the ocean and help maintain its average pH at 8.1 (slightly acidic or basic)
List the components (reservoirs) of the hydrologic cycle that hold water on processes by which water moves among these reservoirs.
Recycle water among the ocean, atmosphere and the continents.
In water vapor, there is no interconnectedness of individual water molecules (no hydrogen bonds).
TRUE
Latent heat can be absorbed or released only as water undergoes the process of changing state (e.g., as water changes from a liquid to a solid)
TRUE
What are the three factors that affect seawater density? Describe how each factor influences seawater density, including which one is the most important.
Temperature: as it increases the seawater density decreases due to thermal expansion and inverse relationship (variables are inversely proportional). -Salinity: as it increases, seawater density increases due to addition of more dissolved material. -Pressure: as it increases, seawater density increases due to the compressive effects of pressure (2)Temperature has the greatest influence on seawater density because the range of surface seawater temperature is greater than that of salinity.
HEAT:
The amount of energy transferred from one body to another due to a difference in temperature. Heat is proportional to the average KINETIC ENERGY
CALORIE:
The amount of heat required to raise the temperature of 1 gram (10 drops) of water.
What is the average salinity of seawater? What units are normally used, and why are those units useful?
The average salinity of seawater is 3.5% or 220 times saltier than freshwater. Salinity is measured using a salinometer and is expressed in PARTS PER THOUSAND (0/00). You would say 3.55% as 35 0/00. The advantages of this expressing in parts per thousand are that decimals are often avoided, and value convert directly to grams of salt per kilogram of seawater. Salinity values are reported at p.s.u., or practical salinity units, which are equal to parts per thousand.
In what ways are seawater and pure water similar? How are the two different?
The color of pure water and seawater are identical along with most of its physical properties at seawater is 96.5% water. Seawater freezes at a lower temp of 1.9 C (28.6 F) than pure water 0 C (32 F) Seawater boils at a higher temp 100.6 C (213.1 F) than pure water 100 C (212 F). Density increases in pure water when substances are added and dissolved due to more mass being added per unit volume. Not true of seawater.
TEMPERATURE
The direct measure of the average kinetic energy of the molecules that make up a substance. Temperature changes when heat is added or removed, the greater the temperature the greater the kinetic energy. Measured in Centigrade or Fahrenheit.
Which of the following terms describes a rapid change in salinity with depth?
The halocline represents a rapid change of salinity with depth
How does the specific heat capacity of water compare with that of other substances? Describe the effect this has on climate.
The specific heat of pure water is high where other common substances have a much lower specific heat. Substances with high heat capacity can absorb or lose large amounts of heat with little change in temperature. This is measured by specific heat or heat capacity per unit mass of a body.
Discuss how the dipolar nature of a water molecule makes it such an effective solvent of ionic compounds.
Water molecules being both negatively and positively charged, interact with other water molecules and other polar molecules and are able to dissolve nearly everything. They can reduce the attraction between ions of opposite charge in other substances.
Describe what condition exists in water molecules to make them dipolar
Water molecules have a bent geometry that gives a slight negative charge at one end and a slight positive charge at the other end.
The density of seawater increases with ________ in temperature and ________ in salinity.
a decrease; an increase
Halocline
a layer of water in which the salinity changes rapidly with changes in depth
Pycnocline
a layer of water in which there is a rapid change of density with depth
Where is the salinity of ocean surface waters highest?
about 25 degrees north or south of the equator
The Baltic Sea has ____________ because of ______________
brackish water; large amounts of runoff
Each hydrogen atom shares its single electron with electrons in the oxygen atom. Which type of bond is this?
covalent bond
Which of the following increases the salinity of seawater?
evaporation of seawater
There is no pycnocline in _______ latitude regions because _____________.
high-; the water column is uniformly cold and dense
The Red Sea has ____________ water because of large amounts of ______________.
hypersaline; evaporation
In an atom, the nucleus is composed of _____________ and _____________, and the ____________ orbit very quickly around the nucleus.
protons; neutrons; electrons
A layer of rapid change of ocean density with depth is called a....
pycnocline is a layer of rapidly changing seawater density.
