Water Behavior in Soils: Difference between revisions
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'''Chemical Properties of Water and Behavior in Soils''' | '''Chemical Properties of Water and Behavior in Soils''' | ||
The chemical properties of water govern its behavior in the environment and control many key processes occurring in soils as the aqueous phase interacts with organisms, mineral surfaces, and air spaces.As a result of its nonlinear structure and dipole moment, water has a high dielectric constant (80.1 at 20°C).This unique property of water also makes it a powerful solvent, allowing it to readily dissolve ionic solids. | The chemical properties of water govern its behavior in the environment and control many key processes occurring in soils as the aqueous phase interacts with organisms, mineral surfaces, and air spaces.As a result of its nonlinear structure and dipole moment, water has a high dielectric constant (80.1 at 20°C).This unique property of water also makes it a powerful solvent, allowing it to readily dissolve ionic solids. | ||
Another particularly important chemical property of water that impacts processes occurring within the soil solution is that it is amphoteric, meaning that it can act as either an acid or a base (IUPAC 1997). Due to its polarity, water readily undergoes ionic dissociation into protons and hydroxide ions (Eisenberg & Kauzmann 1969, Pauling 1988): | |||
H2O(l) ↔ H+(aq) + OH-(aq) (1) | |||
Accordingly, when it reacts with a strong base, water acts as an acid, releasing protons: | |||
H2O(l) + NH3 ↔ NH4+(aq) + OH-(aq) (2) | |||
When it reacts with a strong acid, water acts as a base, accepting protons: | |||
H2O(l) + HCl ↔ H3O+(aq) + Cl-(aq) (3) | |||
The amphoteric behavior of water facilitates the acid-base chemistry and dictates the potential pH range of aqueous solutions, thereby imparting soil pH — a "master variable" of soils that influences soil formation, plant growth, and environmental quality (Sparks 2003). | |||
Revision as of 18:18, 19 April 2018
Chemical Properties of Water and Behavior in Soils The chemical properties of water govern its behavior in the environment and control many key processes occurring in soils as the aqueous phase interacts with organisms, mineral surfaces, and air spaces.As a result of its nonlinear structure and dipole moment, water has a high dielectric constant (80.1 at 20°C).This unique property of water also makes it a powerful solvent, allowing it to readily dissolve ionic solids. Another particularly important chemical property of water that impacts processes occurring within the soil solution is that it is amphoteric, meaning that it can act as either an acid or a base (IUPAC 1997). Due to its polarity, water readily undergoes ionic dissociation into protons and hydroxide ions (Eisenberg & Kauzmann 1969, Pauling 1988):
H2O(l) ↔ H+(aq) + OH-(aq) (1) Accordingly, when it reacts with a strong base, water acts as an acid, releasing protons: H2O(l) + NH3 ↔ NH4+(aq) + OH-(aq) (2) When it reacts with a strong acid, water acts as a base, accepting protons: H2O(l) + HCl ↔ H3O+(aq) + Cl-(aq) (3) The amphoteric behavior of water facilitates the acid-base chemistry and dictates the potential pH range of aqueous solutions, thereby imparting soil pH — a "master variable" of soils that influences soil formation, plant growth, and environmental quality (Sparks 2003).