Advanced Instruments 3300, Руководство пользователя

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Definitions
Solution : A homogeneous mixture of solute and solvent in which the
solvent is usually the major component, and the solute is the minor one.
Concentration : The ratio of solute to a given amount of solvent
(molal), or ratio of solute to solution (molar).
The amount of solute is usually expressed in terms of moles, i.e., gram
molecular weights. One mole = 6.028 x 10
23
molecules (Avogadro's
number). One mole of glucose (180.2 g) and one mole of sodium chlo-
ride (58.4 g) each contain Avogadro's number of molecules.
Common units of concentration are:
• Molality : Moles of solute per kilogram of pure solvent.
• Osmolality : Osmols of solute particles per kilogram of pure sol-
vent. As noted above, most ionic solutes do not completely dis-
sociate. Osmolality is a unit of concentration that takes into
account the dissociative effect. Osmolality is usually expressed
in mOsm/kg H
2
O. One milliosmol (mOsm) is 10
-3
osmols.
Osmolality is defined as:
where:
ø = osmotic coefficient, which accounts for the degree of mole-
cular dissociation.
n = number of particles into which a molecule can dissociate.
C = molal concentration of the solution.
• Molarity : Moles of solute per liter of solution.
• Osmolarity : Osmols of solute particles per liter of solution.
Although molarity and osmolarity may be common units of
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Advanced
®
Osmometer Model 3300 User’s Guide
O H kg
osmol
nC Osmolality
2
= = φ