Gonotec Gmbh, Germany

OSMOMAT 070 VAPOUR PRESSURE OSMOMETER

OSMOMAT 070 VAPOUR PRESSURE OSMOMETER for the determination of average molecular weights of polymers in the range of 50-50,000 daltons in toluene in organic solvents with high precision and ease of operation and determination of osmolality of aqueous solutions

DESCRIPTION

OSMOMAT 070 VAPOUR PRESSURE OSMOMETER for the determination of average molecular weights of polymers in the range of 50-50,000 daltons in toluene in organic solvents with high precision and ease of operation and determination of osmolality of aqueous solutions.

MEASUREMENT PRINCIPLE

The vapor pressure method is suitable for the determination of the average molecular weight of polymers which are soluble in a variety of different organic solvents and for the determination of osmolality of aqueous solutions.

Two thermistors, connected for difference measurement, are suspended in a thermostated measuring cell, which is filled with the saturated vapor of the solvent. The measuring probes, which are first covered with solvent droplets, will adapt to the cell temperature.

There is no temperature difference between the two probes. Exchanging the solvent droplet of one of the probes by a droplet of the solution will lead to condensation of solvent vapor due to the lower vapor pressure of the solvent above the solution. The released condensation enthalpy increases the temperature of the solution droplet, which simultaneously leads to an increase of the vapor pressure.

After reaching the vapor pressure equilibrium of the solution droplet, a relative stable temperature is obtained at the solution droplet. This temperature is converted by the measuring system to a direct voltage signal and  thereby as a measuring value at the user’s disposal. The resulting relative measuring value is nearly proportional to the osmolal concentration of the solutions, may be however affected by heat loss and non ideal behaviour of the polymer solutions.

By calibrating with solutions of known molality and osmolality and by means of a final statistical calculation of the measuring value, the nonlinear behaviour may be eliminated.

MAJOR MERITS

1. Two thermistors of high resolution for precise measurement of temperature difference for reliable results

2. Auto zero adjustment of the measuring system for greater convenience and ease of operation

3. The cell temperature adjustable in steps of 1°C in the temperature range 30°C and 130°C, permits measurement of different samples, including electrically conducting liquids

4. Wheatstone bridge based measurement, and display temperature difference with a high resolution of 5×10-5°C

5. Thermostating of the cell with very high temperature constant, helps in reliable measurement

6. Shares semi automated control unit SA, with 070, with companion unit Osmomat 090 membrane osmometer saving significant cost

LOWEST MEASURABLE CONCENTRATION

Toluene: 3.3 x 10-5 Mol/kg
Water: 1.7 x 10-4 Mol/kg

MOLECULAR WEIGHT RANGE

Toluene: 50 – 50.000 Dalton
Water: 50 – 5.000 Dalton

SAMPLE VOLUME

approximately 1 mL per solution, at least 3 solutions in graduated molal concentration

SP. VP OF THE SAMPLE

<0.1% of the solvent used

CALIBRATION SUBSTANCES

Benzil

 APPLICATIONS

1. Average molecular weight of polymers, soluble in different organic solvents

2. Osmolality of aqueous solutions

To know more about Osmomat 070 Vapour Pressure Osmometer:

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