Practical investigations
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Like you've suggested, I have done the acid-base titration to see whether the concentration of ethanoic acid in wine has increased or not. The concentration was 0.5% and did not change. I have tested on wine that has been exposed in air for 1 day, 3 weeks, 1 month, 6 months.
All showed the same result - the ethanoic acid concentration virtually did not change at all while the ethanol concentration decreased to 3% after only 1 month. Can you suggest any reason for this? Thank you very much.
Igloo writes ...
Obviously our theory about the bacterial oxidation of ethanol in the wine to ethanoic acid, as being the cause of the decrease in the concentration of ethanol, does not appear to be observed in practice. Here are two alternative ideas:
[1] Over time, ethanol simply volatilises away. It is, after all, more volatile than water.
[2] Perhaps the ethanol is only partially oxidised to ethanal, rather than ethanoic acid.
Your experimental findings showing that the concentration of ethanoic acid remains approximately constant is of course worth mentioning in your report. “Negative” results such as these are almost as valuable to a researcher as “positive” ones.
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updated: 17 December 2006
