In studying aquatic chemistry, there are many applications for chemical equilibria.
For instance, it is possible to be looking into the mechanisms that control the
movement of solutes in groundwater or surface water; or one could be interested in
controlling the pH, alkalinity or corrosivity of drinking water; or one may be interested
in the toxicological effects of dissolved metals on the biota. Actually, there are so
many possible applications of chemical equilibria to aqueous systems that it would be
hard to list them all.
For a person interested in aquatic systems (or soil systems, or marine systems, for
that matter) a few assumptions hold true: Dissolved ions in solution interact with each
other (form complexes), interact with particulate surfaces (adsorb) and possibly form
solid phases (precipitate). In a typical natural
system, say a stream water, there may be 10 to
20 major chemical components dissolved in solution. These components have the
potential to form hundreds of dissolved chemical complexes, solids phases or
adsorbed species. Some of these chemical species may be biologically active or
even toxic while others may be inert. All of this depends on factors like the total
concentration of each component, the pH, pe, ionic strength and temperature.
This is where calculating chemical equilibrium is helpful. As the name implies,
chemical equilibrium assumes that all reactions have gone to completion and are
in equilibrium with one another. So time dependent reactions -- those reactions
that have kinetic restrictions -- are not addressed in this approach. In essence, the
chemical equilibrium approach provides you with a thermodynamic snapshot of your system: the pH, ionic strength, the
distribution of dissolved chemical species, how much solid phase formed, etc. This is the type of information that is
critical to understanding what happens chemically in water.
In studying aquatic chemistry, there are many applications for chemical equilibria. For instance, it is possible to be
looking into the mechanisms that control the movement of solutes in groundwater or surface water; or one could be
interested in controlling the pH, alkalinity or corrosivity of drinking water; or one may be interested in the toxicological
effects of dissolved metals on the biota. Actually, there are so many possible applications of chemical equilibria to
aqueous systems that it would be hard to list them all.
For a person interested in aquatic systems (or soil systems, or marine systems, for that matter) a few assumptions hold
true: Dissolved ions in solution interact with each other (form complexes), interact with particulate surfaces (adsorb)
and possibly form solid phases (precipitate). In a typical natural system, say a stream water, there may be 10 to 20
major chemical components dissolved in solution. These components have the potential to form hundreds of dissolved
chemical complexes, solids phases or adsorbed species. Some of these chemical species may be biologically active or
even toxic while others may be inert. All of this depends on factors like the total concentration of each component, the
pH, pe, ionic strength and temperature.
This is where calculating chemical equilibrium is helpful. As the name implies, chemical equilibrium assumes that all
reactions have gone to completion and are in equilibrium with one another. So time dependent reactions -- those
reactions that have kinetic restrictions -- are not addressed in this approach. In essence, the chemical equilibrium
approach provides you with a thermodynamic snapshot of your system: the pH, ionic strength, the distribution of
dissolved chemical species, how much solid phase formed, etc. This is the type of information that is critical to
understanding what happens chemically in water.
In studying aquatic chemistry, there are many applications for chemical equilibria. For instance, it is possible to be
looking into the mechanisms that control the movement of solutes in groundwater or surface water; or one could be
interested in controlling the pH, alkalinity or corrosivity of drinking water; or one may be interested in the toxicological
effects of dissolved metals on the biota. Actually, there are so many possible applications of chemical equilibria to
aqueous systems that it would be hard to list them all.
For a person interested in aquatic systems (or soil systems, or marine systems, for that matter) a few assumptions hold
true: Dissolved ions in solution interact with each other (form complexes), interact with particulate surfaces (adsorb)
and possibly form solid phases (precipitate). In a typical natural system, say a stream water, there may be 10 to 20
major chemical components dissolved in solution. These components have the potential to form hundreds of dissolved
chemical complexes, solids phases or adsorbed species. Some of these chemical species may be biologically active or
even toxic while others may be inert. All of this depends on factors like the total concentration of each component, the
pH, pe, ionic strength and temperature.
This is where calculating chemical equilibrium is helpful. As the name implies, chemical equilibrium assumes that all
reactions have gone to completion and are in equilibrium with one another. So time dependent reactions -- those
reactions that have kinetic restrictions -- are not addressed in this approach. In essence, the chemical equilibrium
approach provides you with a thermodynamic snapshot of your system: the pH, ionic strength, the distribution of
dissolved chemical species, how much solid phase formed, etc. This is the type of information that is critical to
understanding what happens chemically in water.
In studying aquatic chemistry, there are many applications for chemical equilibria. For instance, it is possible to be
looking into the mechanisms that control the movement of solutes in groundwater or surface water; or one could be
interested in controlling the pH, alkalinity or corrosivity of drinking water; or one may be interested in the toxicological
effects of dissolved metals on the biota. Actually, there are so many possible applications of chemical equilibria to
aqueous systems that it would be hard to list them all.
For a person interested in aquatic systems (or soil systems, or marine systems, for that matter) a few assumptions hold
true: Dissolved ions in solution interact with each other (form complexes), interact with particulate surfaces (adsorb)
and possibly form solid phases (precipitate). In a typical natural system, say a stream water, there may be 10 to 20
major chemical components dissolved in solution. These components have the potential to form hundreds of dissolved
chemical complexes, solids phases or adsorbed species. Some of these chemical species may be biologically active or
even toxic while others may be inert. All of this depends on factors like the total concentration of each component, the
pH, pe, ionic strength and temperature.
This is where calculating chemical equilibrium is helpful. As the name implies, chemical equilibrium assumes that all
reactions have gone to completion and are in equilibrium with one another. So time dependent reactions -- those
reactions that have kinetic restrictions -- are not addressed in this approach. In essence, the chemical equilibrium
approach provides you with a thermodynamic snapshot of your system: the pH, ionic strength, the distribution of
dissolved chemical species, how much solid phase formed, etc. This is the type of information that is critical to
understanding what happens chemically in water.
In studying aquatic chemistry, there are many applications for chemical equilibria. For
instance, it is possible to be looking into the mechanisms that control the movement of
solutes in groundwater or surface water; or one could be interested in controlling the
pH, alkalinity or corrosivity of drinking water; or one may be interested in the
toxicological effects of dissolved metals on the biota. Actually, there are so many
possible applications of chemical equilibria to aqueous systems that it would be hard to
list them all.
For a person interested in aquatic systems (or soil systems, or marine systems, for that
matter) a few assumptions hold true: Dissolved ions in solution interact with each other
(form complexes), interact with particulate surfaces (adsorb) and possibly form solid
phases (precipitate). In a typical natural system, say a stream water, there may be 10 to
20 major chemical components dissolved in solution. These components have the
potential to form hundreds of dissolved chemical complexes, solids phases or adsorbed
species. Some of these chemical species may be biologically active or even toxic while
others may be inert. All of this depends on factors like the total concentration of each
component, the pH, pe, ionic strength and temperature.
This is where calculating chemical equilibrium is helpful. As the name implies, chemical
equilibrium assumes that all reactions have gone to completion and are in equilibrium
with one another. So time dependent reactions -- those reactions that have kinetic
restrictions -- are not addressed in this approach. In essence, the chemical equilibrium
approach provides you with a thermodynamic snapshot of your system: the pH, ionic strength, the distribution of
dissolved chemical species, how much solid phase formed, etc. This is the type of information that is critical to
understanding what happens chemically in water.
In studying aquatic chemistry, there are many applications for chemical equilibria. For
instance, it is possible to be looking into the mechanisms that control the movement of
solutes in groundwater or surface water; or one could be interested in controlling the pH,
alkalinity or corrosivity of drinking water; or one may be interested in the toxicological
effects of dissolved metals on the biota. Actually, there are so many possible
applications of chemical equilibria to aqueous systems that it would be hard to list them
all.
For a person interested in aquatic systems (or soil systems, or marine systems, for that
matter) a few assumptions hold true: Dissolved ions in solution interact with each other
(form complexes), interact with particulate surfaces (adsorb) and possibly form solid
phases (precipitate). In a typical natural system, say a stream water, there may be 10 to
20 major chemical components dissolved in solution. These components have the potential to form hundreds of
dissolved chemical complexes, solids phases or adsorbed species. Some of these
chemical species may be biologically active or even toxic while others may be inert. All of
this depends on factors like the total concentration of each component, the pH, pe, ionic
strength and temperature.
This is where calculating chemical equilibrium is helpful. As the name implies, chemical
equilibrium assumes that all reactions have gone to completion and are in equilibrium
with one another. So time dependent reactions -- those reactions that have kinetic
restrictions -- are not addressed in this approach. In essence, the chemical equilibrium
approach provides you with a thermodynamic snapshot of your system: the pH, ionic strength, the distribution of
dissolved chemical species, how much solid phase formed, etc. This is the type of information that is critical to
understanding what happens chemically in water.
How Can Chemical Equilibrium
Help You?
In studying aquatic chemistry, there are many applications for chemical equilibria.  For instance, it is possible to be looking into the mechanisms that control the movement of solutes in groundwater or surface water; or one could be interested in controlling the pH, alkalinity or corrosivity of drinking water; or one may be interested in the toxicological effects of dissolved metals on the biota. Actually, there are so many possible applications of chemical equilibria to aqueous systems that it would be hard to list them all.

For a person interested in aquatic systems (or soil systems, or marine systems, for that matter) a few assumptions hold true: Dissolved ions in solution interact with each other (form complexes), interact with particulate surfaces (adsorb) and possibly form solid phases (precipitate). In a typical natural system, say a stream water, there may be 10 to 20 major chemical components dissolved in solution. These components have the potential to form hundreds of dissolved chemical complexes, solids phases or adsorbed species. Some of these chemical species may be biologically active or even toxic while others may be inert. All of this depends on factors like the total concentration of each component, the pH, pe, ionic strength and temperature.
This is where calculating chemical equilibrium is helpful. As the name implies, chemical equilibrium assumes that all reactions have gone to completion and are in equilibrium with one another. So time dependent reactions -- those reactions that have kinetic restrictions -- are not addressed in this approach. In essence, the chemical equilibrium approach provides you with a thermodynamic snapshot of your system: the pH, ionic strength, the distribution of dissolved chemical species, how much solid phase formed, etc. This is the type of information that is critical to understanding what happens chemically in water.
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