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Hydration is accompanied by the release of heat and a decrease in entropy
of the solvent due to the orderly arrangement of water molecules in the hydrated
layer.
Hydration shell is mainly held by electrostatic forces of attraction, and the
polar group may form hydrogen bonds with water molecules.
The most strongly associated with ions or polar groups in the solute
molecules are water molecules which are concentrated in the first molecular
layer; the binding energy of the molecules of the second layer is much lower; in
the third it is already negligible.
In the hydration ions often form coordination compounds. For example,
hydration Cu 2+ ion in aqueous solution occurs so that the four water molecules
are distributed symmetrically around the Cu2+to form a flat shape.
The hydrated copper ion Cu2 + - 4H2O solution gives a characteristic blue
color. The formation of hydrates (solvates) underlies the theory of solutions
Mendeleev.
The most firmly bound hydrate water may solute in the crystallization from
solutions comprise its crystals (crystal water) to form crystalline hydrates, such
as CuSO
4
-
5
H
2
O, which essentially are complex compounds.
The degree of hydration of different ions and molecules, and varies
depending on the particle size and the magnitude of their charge. The higher
charge and smaller ion sizes, i.e. higher specific charge density, the greater the
degree of hydration. L + ion hydrated more specific because it has a charge
density higher than that of K +ions.
Undissociated molecules in varying degrees hydrated their hydrate shell
occurs only around the polar groups and therefore can not be continuous.
Hydration of ions in solution affects their mobility, and inversely
proportional relationship.
Biopolymers - class of polymers found in nature in its natural form, a part
of living organisms, proteins, nucleic acids, polysaccharides, lignin.
Biopolymers are composed of the same (or similar) units - monomers.
Monomers proteins - amino acids, nucleic acids - the nucleotides in
polysaccharides - monosaccharides.
There are two types of biopolymers - regular (some polysaccharides) and
irregular (proteins, nucleic acids, some polysaccharides).
Proteins have several levels of the organization - primary, secondary,
tertiary, and quaternary sometimes.
The primary structure is determined by the sequence of monomers, the
secondary is given by intra- and intermolecular interactions between monomers,
typically by hydrogen bonds.
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