Alcoholometry with a Refractometer in vinegar

Accurate Determination of Alcohol with Semimicro Still and Refractometer

The determination of the remaining alcohol content in vinegar can be done with simple means at home. But it’s not possible to determine accurately the alcohol content if using directly measurement methods like an alcoholometer (hydrometer), refractometer, or vinometer because in all cases the containing acetic acid, dissolved sugar, and extract distort the measurement. Therefore previously the vinegar sample has to be neutralized and distilled. The distillate is free of distorting substances, so the indicated value of the measurement device like a refractometer is true. But the volume of the sample has changed due to titration and distillation (though not the amount of alcohol when distilling completely), so the value has to be converted accordingly.


Calculation example:

Volume of the titrated vinegar sample: 10.00 ml
Sodium hydroxide solution consumed: 7.44 ml
Volume before distillation: 0.50 ml
Alcohol content of the distillate: 0.80 %vol
Volume of the distillate: 0.41 ml

The alcohol content of the sample is 1.10 %vol

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