Practical investigations
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I am investigating the acidity of wine and I found that over a period of one week it has increased. The only reason seems to be the oxidation of ethanol to ethanoic acid, but I don’t understand what the oxidising agent is because the text book says a strong oxidising agent is needed, and I can’t find one that would be in wine. Any ideas?
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Igloo replies
The text book is correct in that if the oxidation is to be carried out in a relatively short period of time then a strong oxidising agent is needed, such as acidified sodium dichromate solution.
However, oxygen in the air is responsible for the slower oxidation which can occur in wines because of the presence of what are known as “vinegar bacteria”. These microbes convert ethanol into ethanoic acid and effectively turn the wine into vinegar. Vinegar bacteria are one of the primary wine spoilage organisms, and restricting oxygen can control them. This is why wine is stored in sealed containers, and these tend to be kept full to eliminate air and therefore prevent vinegar formation.
Risk assessment
Before attempting any practical work based on the advice and suggestions on this website, you must do the following. Identify any hazards, assess the risks from these hazards, and then decide appropriate control measures to reduce the risks. You must have these approved by those in authority in your school or college laboratory. Do not rely on what is said on this website.
For further guidance see our tutorial on Risk Assessment.
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updated: 01 February 2008
