Oceanography ch 7 terms

Solution

A homogeneous mixture of two or more substances; made of a solute and a solvent

ion

An atom or group of atoms that has a positive or negative charge.

salinometer

An electronic device that determines salinity by measuring the electrical conductivity of a seawater sample.

which dissolved gas is present in the ocean in much greater proportion then in the atmosphere?

CO2

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

what dissolved gases are most abundant in the ocean?

Nitrogen is the most abundant dissolved gas in seawater, oxygen is second

solids dissolve more readily in warm water than in cool. does this also hold true for gases?

No, gases dissolved more easily in cool water.

What are some of water's colligative properties? Does pure water have colligative properties?

Pure water does not have these properties. Seawater's properties are: as salinity increases, freezing point decreases and evaporation slows.

How are chemical methods of determining salinity dependent on the principle of constant proportions?

Salinity can be determined by evaporating water and measuring the leftover solids (or salts). due to The principle of constant proportions the measurement of only one constituent is needed to find the salinity of water

mixing time

The time necessary to mix a substance through the ocean, about 1,600 years.

Salinity

The total amount of dissolved inorganic solids in a water sample.

technically, there are no "salts" in seawater. How can that be?

There are no "salts" in seawater because sodium dissolves to make a solution in water so its actually solution of sodium and chloride ions

How is salinity determined?

They measure chlorinate (the chloride ion) because its easier to measure and always account for the same proportion of dissolved solids

What's a buffer? Why is seawater's buffering capacity important to marine life?

a buffer is a group of substances that tends to resist change in the ph of a solution. Buffering prevents broad swings of ph when acids or bases are introduced into the ocean

Alkaline

a solution containing a base

ph scale

acidity or alkalinity of a solution measured

Forchhammer's Principle

aka the principal of constant proportions. the percentage of various salts in seawater is the same in samples from many places, regardless of how salty the water is

other than hydrogen and oxygen what are the most abundant ions in seawater?

chloride, sodium, sulfate, magnesium, and calcium

How are seawaters conservative constituents different from its nonconservative constituents? ex.

conservative change slowly thru time ex. major ions in seawater nonconservative change quickly due to chemical processes ex. gases in seawater

what are the sources of the oceans dissolved solids?

derived from erosion and weathering of ocean basins and the contact of seawater with hot minerals at mid-ocean rifts

mixture

different substances are closely intermingled but retain separate identities

Theres lots of oxygen in water. why cant fish breath that? Why do they have to breathe oxygen dissolved in the water?

fish "breath" the dissolved o2 out of the water using their gills fish are cold blooded which reduces their oxygen demands

how does a solution differ from a mixture

in a true solution the molecules are homogeneously dispersed among the solute and solvent. In mixture the different substances are closely intermingled but not blended together (heterogenous)

what might be some of the consequences of ocean acidification?

increasing acidity decreases the concentration of calcium carbonate in the water, making it unavailable to organisms for the construction of some hard parts. the production of coral reefs are in particular danger

what happens when carbon dioxide dissolves in seawater?

initially co2 and water combine to form carbonic acid. carbonic acid then breaks into a bicarbonate ion and a hydrogen ion. most co2 dissolved not seawater end up bicarbonate.

How is pH expressed?

it measures the concentration of hydrogen ions in a solution. an excess of hydrogen ions is acidic an excess of hydroxide ions makes alkaline.

precipitating

solute material reforming into crystals

Base

substance that combines with a hydrogen ion in solution that has more hydroxide ions

Acid

substance that releases a hydrogen ion in solution has an excess of hydrogen ions

nonconservative constituents

substances dissolved in seawater that are tied to biological or seasonal cycles or to very short geological cycles

What is meant by "residence time"? does seawater itself have a residence time?

the average length of time an atom of an element spends in the ocean. seawater has a residence time of 4100 yrs

residence time

the avg length of time an atom of an element spends in the ocean

excess volatiles

the components of ocean water whose proportions are not accounted for by the weathering of surface rocks

ionic bonds

the electrostatic attraction that exists between ions that have opposite charge

colligative properties

the four properties which vary with the quantity of solutes dissolved in the water/solutions.

hydrologic cycle

the movement of water through the biosphere (water cycle)

chemical equilibrium

the proportion and amounts of dissolved salts per volume of ocean are nearly constant and have been so for mill of yrs

Saturation

the rate at which molecules of the solute are being dissolved equals the rate at which they are precipitating at another location in the solution

what was the earthly origin of the sodium and chloride ions in common table salt?

the sodium and chorine comes from rocks and minerals (halite) decomposed by normal weathering processes, esp. in the oceans. The ocean is the largest reservoir of nacl

How is seawater's salinity expressed?

the total concentration of dissolved inorganic solids in water is its salinity. Ocean's varies from 3.3%-3.7%

Why is oxygen sometimes in short supply in the tropical ocean? Might this shortage affect marine life?

the tropical ocean is very warm. dissolved oxygen concentrations in parts of the tropical ocean may be so low that animals may be unable to survive; tropical waters are also stressed by pollutants

conservative constituents

those constituents of seawater that occur in constant proportion or change very slowly through time

solute

usually a dissolved gas or solid, less abundant

solvent

usually a liquid, the more abundant part of a solution

example of water in a very short, rapid part of a hydrologic cycle. example of a long and slow hydrologic cycle?

water is likely to stay a short time in the vaporized state and likely to stay a long time in the ocean, deep lakes, or as glaciers

How does a crystal of common salt dissolve in water?

when salt is put in water the positively charged h end of the polar water molecule is attracted to the negatively charged cl-ion, and the negatively charged o end is attracted to the positive na+ion. The ions are surrounded by water molecules that are attracted to them, and become solute ions in the solvent

what factors affect seawater's ph? how does the ph of seawater change with depth? why?

with cold temps, high pressure, and no photosynthetic plants to remove it, co2 will reduce the ph of water, making it less alkaline with depth

Can carbon dioxide be stored in the ocean? How does the amount of carbon dioxide in the ocean compare to the amount in the atmosphere?

yes. there is about 60 times as much co2 dissolved in the ocean as in the atmosphere