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Glossary of Chemical Oceanography Terms
IV. Ionic Interactions in Seawater
Activity: The effective concentration of a given solute. Thermodynamically, it is related
to the product of the concentration and an activity coefficient that describes the
magnitude of the nonideal behavior of the solute with the solvent (it is defined as 1
for an ideal solution, with activity = concentration).
Activity Coefficient: The quantity that accounts for the nonideal behavior of a solute in
solution. It is defined as 1 when the concentration approaches 0.
Association Constant: The thermodynamic constant for the formation of an ion pair or
complex (A + B→ AB, K A = [AB]/[A][B]).
Baseline Study: A study to determine the concentration or state of a system before it is
affected by the influence of humans.
Bioavailability: The availability of an element needed by an organism for its growth or
well- being.
Boiling Point Elevation: The increase in the boiling point temperature as the result of the
presence of a solute.
Boiling Point Temperature: The temperature at which the vapor pressure of a liquid is
equal to the atmospheric pressure or other external pressure.
Born–Haber Cycle: The cycle of the changes in energy that occur when a crystalline substance is formed from the constituent elements (considers the heat of sublimation,
heat of ionization, electron affinity, heat of formation, and lattice energy).
Boyle’s Law: The pressure of a given mass of a gas is inversely proportional to the volume.
Charles Law: The volume of a given mass of a gas is directly proportional to the absolute
temperature.
Clathrate Water Structure Model: Originally postulated by Linus Pauling. The model
suggests that the structure of water is an equilibrium between monomers in a
clathrate hydrate cage. The discrete sites inside of the clathrate can serve as a host
for individual water molecules.
Cluster Expansion Model: This model attempts to account for all the possible interactions that can occur between ions in solution (plus–minus, plus–plus, and minus–
minus) and makes no attempt to separate coulombic and noncoulombic terms.
Cluster Water Structure Model: The model assumes that the structured form of water
is a group of hydrogen- bonded water clusters in equilibrium with monomers
(i.e., Frank and Wen model).
Complexed Ions: Ions that interact covalently with ligands (e.g., a metallic cation interacting with EDTA).
Compressibility: The change in the volume (V) of a substance from the application of
pressure (β = –(1/V)(∂V/∂P).
Contact Ion Pair: When the ions in an ion pair are in contact and linked electrostatically
(little or no covalent bonding).
Continuum Model: The model that assumes that water is a continuous dielectric medium
with no structure.
Covalent- Bonded Ion Pair: When the ions of an ion pair in contact share electrons
(covalent character).
Cross- Square Rule: Σ ▫ = Σ X. The sum of the excess mixing properties around the sides
of the diagram is equal to the sum of the excess properties of the cross mixtures.
Dalton’s Law: The total pressure of a mixture of gases is equal to the sum of the partial
pressure of the components of the mixture.
Glossary of Chemical Oceanography Terms
IV. Ionic Interactions in Seawater
Activity: The effective concentration of a given solute. Thermodynamically, it is related
to the product of the concentration and an activity coefficient that describes the
magnitude of the nonideal behavior of the solute with the solvent (it is defined as 1
for an ideal solution, with activity = concentration).
Activity Coefficient: The quantity that accounts for the nonideal behavior of a solute in
solution. It is defined as 1 when the concentration approaches 0.
Association Constant: The thermodynamic constant for the formation of an ion pair or
complex (A + B→ AB, K A = [AB]/[A][B]).
Baseline Study: A study to determine the concentration or state of a system before it is
affected by the influence of humans.
Bioavailability: The availability of an element needed by an organism for its growth or
well- being.
Boiling Point Elevation: The increase in the boiling point temperature as the result of the
presence of a solute.
Boiling Point Temperature: The temperature at which the vapor pressure of a liquid is
equal to the atmospheric pressure or other external pressure.
Born–Haber Cycle: The cycle of the changes in energy that occur when a crystalline substance is formed from the constituent elements (considers the heat of sublimation,
heat of ionization, electron affinity, heat of formation, and lattice energy).
Boyle’s Law: The pressure of a given mass of a gas is inversely proportional to the volume.
Charles Law: The volume of a given mass of a gas is directly proportional to the absolute
temperature.
Clathrate Water Structure Model: Originally postulated by Linus Pauling. The model
suggests that the structure of water is an equilibrium between monomers in a
clathrate hydrate cage. The discrete sites inside of the clathrate can serve as a host
for individual water molecules.
Cluster Expansion Model: This model attempts to account for all the possible interactions that can occur between ions in solution (plus–minus, plus–plus, and minus–
minus) and makes no attempt to separate coulombic and noncoulombic terms.
Cluster Water Structure Model: The model assumes that the structured form of water
is a group of hydrogen- bonded water clusters in equilibrium with monomers
(i.e., Frank and Wen model).
Complexed Ions: Ions that interact covalently with ligands (e.g., a metallic cation interacting with EDTA).
Compressibility: The change in the volume (V) of a substance from the application of
pressure (β = –(1/V)(∂V/∂P).
Contact Ion Pair: When the ions in an ion pair are in contact and linked electrostatically
(little or no covalent bonding).
Continuum Model: The model that assumes that water is a continuous dielectric medium
with no structure.
Covalent- Bonded Ion Pair: When the ions of an ion pair in contact share electrons
(covalent character).
Cross- Square Rule: Σ ▫ = Σ X. The sum of the excess mixing properties around the sides
of the diagram is equal to the sum of the excess properties of the cross mixtures.
Dalton’s Law: The total pressure of a mixture of gases is equal to the sum of the partial
pressure of the components of the mixture.