1 THE OSMOMAT 070 VAPOR PRESSURE OSMOMETER ...

28 User Guide OSMOMAT 070 Version 1.1
Take 20-25 g of solvent when using glass containers with a volume of about 25 ml.
Example for making calibration solutions:
Using 20 g of solvent results in a net weight of 4.2046 mg or 0.00420 g for a concentration of 1
mMol/kg.
The following net weights should be produced as a result:
2 mMol / kg = 0.00840 g / 20 g of solvent
4 mMol / kg = 0.01681 g / 20 g of solvent
8 mMol / kg = 0.03363 g / 20 g of solvent
12 mMol / kg = 0.05045 g / 20 g of solvent
When making these solutions, try not to use less than 25 ml of solution, because the net weights will
otherwise be too low and the measurement may not be accurate.
The glass containers, and especially the covers, must be suitable for this application.
The covers must close tightly and the sealing material (PTFE) must not dissolve in the solvent being
used.
Record the net weight as follows.
Place the glass jar with cover (screw-cap lid with PTFE foil seal) on the weighing pan and tare the
scale to zero. Next, weigh out the required quantity of benzyl. Make a note of the exact net weight.
After resetting the scale to zero, pipette the required quantity of solvent into the glass jar. Then put the
lid on the jar. Weigh the solvent amount and note its weight.
The following calculation is generated for this solution:
Net weight of benzyl 0.0084 g
Net weight of Toluol 21.6750 g (25 ml, specific weight: 0.867 g/ml)
Weight concentration = 0.0084 g / 21.6750 g x 1000 = 0.388 g/kg
Molal concentration = 0.388 / 210.23 = 0.001846 mol/kg or 1.85 mMol/kg
For the solutions to be accurate, both the substances and solvents have to be weighed out.
Never make solutions with dilution series or volumetric measurement of the solvent.
3.1.6 Making solutions for the sample measurement
Solutions for determining molecular weight are made in the same way as calibration solutions.
As much as possible, you should use the same molal concentrations as you did for calibration. A
standard concentration series for these solutions is
2 mMol/kg, 4 mMol/kg, 8 mMol/kg und 12 mMol/kg.
28 User Guide OSMOMAT 070 Version 1.1