Determination of Sodium Chloride of Glycerin

Sodium Chloride is not usually determined in a crude glycerin. This method for its determination is included for convenience and completeness. The end-point in the sodium chloride titration may be seen more easily if illumination is furnished by a Mazda lamp of suitable size screened by a Wratten safe-light filter no.

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Procedure

Apparatus

1.0 Volumetric Flask 100 ml

2.0 Erlenmeyer Flask 250 ml

3.0 Evaporating dish

4.0 Muffle furnace

5.0 Ashless filter paper

Reagents

1.0 Distilled water

2.0 0.25N NaOH and Sulfuric Acid solution

3.0 Potassium chromate indicator

4.0 0.1N Silver nitrate solution

Determination of Sodium Chloride of Glycerin

Procedure

Weight Accurately 2.0 to 5.0 gm. of well-mixed sample into a tared platinum dish. Dry to constant weight in an air oven at 130°C. or over an Argand burner or in a muffle below a dull red heat (500 - 550°C ) and cool to room temp. in a desiccator.

Dissolve the ash in 25 ml of hot distilled water. Cool to room temp. and into the sample in a 100 ml volumetric flask make up to 100 ml with distilled water. And pipet 50 ml into a 250 ml Erlenmeyer flask.

Add a few drops of phenolphthalein indicator solution and adjust neutrality with 0.25N NaOH and H2SO4 leaving the solution and adjust acid.

Add 1.0 ml of potassium chromate indicator solution and titrate to the first permanent reddish tinge with 0.1N AgNO3.