Model A
2
O
®
Advanced Automated Osmometer User’s Guide
Standard Freezing Curve
ratio can be slowed to prolong the equilibrium time, giving a distinct
plateau height measurable to 0.001°C.
Sensitive thermistor probes monitor the sample temperature and control
the thermoelectric cooling element. Microprocessor control and auto-
mated operation minimize imprecision due to operator technique.
The following Standard Freezing Curve illustrates the temperature of a
sample as it progresses through the freezing cycle and shows the action
of the instrument at each stage of the cycle.
Definitions
Solution: A homogeneous mixture of solute and solvent in which the
solvent is usually the major component, and the solute is the minor
component.
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.
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