Discussion - Spirits, Essential Oils, Vinegar

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Alcohol measurement

Renigald am 30.04.2020 17:59:34 | Region: USA

I seem to be getting bad readings though for titrated vinegar. I titrate the vinegar to pH 7.0, put 0.5 ml into the test

tube with a boiling stone and two drops of anti-foam agent, and then boil it away into the distillation column and syringe. I keep getting 0% alcohol, in the last case I know it was wrong since I added enough alcohol the night before to push the mash alcohol concentration up to 5-6% and the vinegar concentration only increased 1% during the same time.

I am not touching the metal part of the refraktometer or doing anything else I remember from your instructions. Any ideas where I am making a mistake? Thanks!

RE: Alcohol measurement

Helge am 30.04.2020 18:01:46 | Region: Austria
- buy vinegar (a cheap one is goog enough) and mix it with e.g. vodka or
wine, the acid content of the mixture should be between appr. 2 to 5% and the
alcohol content also between appr. 2 to 5%vol. Mix as accurate as possible, so
you’re are able to calculate both values of the mixture, according to the
values stated on the labels of the bought bottels. - And/or buy wine (colour and quality doesn’t matter), adding vinegar is
not necessary. Wine corresponds with appr. 0,5% acetic acid, the alcohol
content is stated on the label of the bottle.

Then do the analysis, the result should correspond with the calculated values. I can imagine, you’ve done the wrong calculation of the analysis, not considering the amount of NaOH-Solution you added. But this is just a guess.
The formula for calculation of a mixture of acetic acid and alcohol you find on page 7 of the description. Please write a short e-mail with the calculation and results of the whole process.
 
By the way, one drop of anti-foam is enough, but it’s not really a
problem if adding two.

RE: Alcohol measurement

Reginald am 30.04.2020 18:02:56 | Region: USA
Thanks for the advice. I found my mistake: the molarity of the NaOH I am
using is too low (0.2 N) so the volume required for titration dilutes the
alcohol % to almost nothing. I will be using 1.0N once it comes in the mail and
this should allow me to factor the volume without over-dilution of the alcohol.
Thanks!
Reggie