Chapter 3: The Unique Nature of Pure Water

polar

A molecule that possesses a dipole moment.

termperature

The average kinetic energy of the particles in a substance. Measured in degrees (C, K, F) usually with a thermometer.

heat

The total kinetic energy, in calories, of all the particles in a substance or object.

calorie

The amount of energy required to raise the temperature of one gram of water one degree.

evaporation

The escape of molecules from the liquid phase into the gaseous phase.

density

The mass of a given volume of a substance.

specific heat

The amount of energy required to raise a mass of substance one degree Celsius.

heat capacity

The amount of heat that must be added to a substance to raise its temperature by a given amount, which reflects the substance's ability to store heat.

evaporative cooling

The lower speed and lower temperature of molecules remaining in the liquid phase after evaporation of the fastest molecules.

cohesion

The sticking together of particles of the same substance.

surface tension

The elastic tendency of liquid.

adhesion

The sticking together of particles of different substances.

viscosity

A liquid's resistance to flow.

salts

A substance that consists of ions that have opposite electrical charges.

ions

An atom or a group of atoms that is electrically charged.

dissociate

The breaking up of a salt molecule into ions when placed in water or other solvents.

deep sound channel

The depth at which sound waves travel slowest, allowing low-frequency waves to travel vast distances.

solutes

Any material dissolved in a solvent.

salinity

The total amount of salts dissolved in seawater. It is generally expressed in parts per thousand (‰).

practical salinity units

Measurement of seawater salinity based on electrical conductivity, measured in parts per thousand.

rule of constant proportions

A principle that states that the relative amounts of ions in seawater are always the same.

precipitation

Atmospheric water that falls to the ground, such as rain and snow.

profile

A graph showing changes in temperature, salinity, or other parameter with depth.

anthropogenic

Human-derived.

nutrient

chemical substance that an organism needs to sustain life

gas exchange

The movement of oxygen and other gases between the atmosphere and the ocean, or between the water or atmosphere and living organisms, in which case it is often called respiratory exchange.

buffering

The shift in the proportion of carbon dioxide and carbonate species which keeps the ocean pH from changing too drastically.

chemical equilibrium

The point in a chemical reaction where amounts of reactants and products is relatively stable and unlikely to change.

ocean acidification

Decrease of seawater pH as a result of increased carbon dioxide.

calcified

Structures containing calcium, usually calcium carbonate.