Physical pharmaceutics
The ability of a solute (a solid, liquid, or gaseous chemical substance present in a smaller
amount) to form a homogeneous solution by dissolving in a solvent (a liquid present in an amount larger
than the solute) is called solubility. The physical and chemical properties of solute and solvent, i.e.,
temperature, pressure, solution pH, and the sub-division state of solute are the influencing factors
of solubility.
General Principles: The solute-solute and solvent-solvent
intermolecular attractive forces should be
A homogeneous mixture of a single
broken before new solute-solvent attractive
phase containing one or more chemical
forces become effective. This breaking and
species dispersed on a molecular scale is
formation of bonds occur simultaneously.
termed a solution. Any one section of the
homogeneous solution possesses properties A solute dissolves in a solvent only when the
completely similar to another section of solute-solute and solvent-solvent attraction
the solution. forces are overcome by the solute-solvent
attraction forces; while a solute does not
The ability of a substance to dissolve is
dissolve if the solute-solvent attraction
termed solubility; the substance being
forces are weaker than the individual solute
dissolved is the solute and the substance
and solvent intermolecular attraction
in which the solute is being dissolved is
forces. The substances are soluble in each
the solvent.
other if all three intermolecular attraction
The process of dissolving involves the forces are somewhat equal.
relative strength of the following 3
intermolecular attractive forces:
1) Solute-solute molecules attractive
forces,
2) Solvent-solvent molecules attractive
forces, and
3) Solute-solvent molecules attractive
forces.
1
The ability of a solute (a solid, liquid, or gaseous chemical substance present in a smaller
amount) to form a homogeneous solution by dissolving in a solvent (a liquid present in an amount larger
than the solute) is called solubility. The physical and chemical properties of solute and solvent, i.e.,
temperature, pressure, solution pH, and the sub-division state of solute are the influencing factors
of solubility.
General Principles: The solute-solute and solvent-solvent
intermolecular attractive forces should be
A homogeneous mixture of a single
broken before new solute-solvent attractive
phase containing one or more chemical
forces become effective. This breaking and
species dispersed on a molecular scale is
formation of bonds occur simultaneously.
termed a solution. Any one section of the
homogeneous solution possesses properties A solute dissolves in a solvent only when the
completely similar to another section of solute-solute and solvent-solvent attraction
the solution. forces are overcome by the solute-solvent
attraction forces; while a solute does not
The ability of a substance to dissolve is
dissolve if the solute-solvent attraction
termed solubility; the substance being
forces are weaker than the individual solute
dissolved is the solute and the substance
and solvent intermolecular attraction
in which the solute is being dissolved is
forces. The substances are soluble in each
the solvent.
other if all three intermolecular attraction
The process of dissolving involves the forces are somewhat equal.
relative strength of the following 3
intermolecular attractive forces:
1) Solute-solute molecules attractive
forces,
2) Solvent-solvent molecules attractive
forces, and
3) Solute-solvent molecules attractive
forces.
1
