A2 Chemistry
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Hi, I’m investigating the concentration of ethanol in a perfume. I've found out the method from information about finding the concentration of ethanol in wine. My method is to dilute the perfume and mix with potassium dichromate. Then add sulfuric acid. Heat that solution in a water bath 40-60mins. After heating add KI and titrate the solution with sodium thiosulphate, using starch to find the end point. What are the other substances, and would the method be suitable to measure the concentration of ethanol in the perfume?
Igloo replies
By “other substances” I assume that you are referring to the perfume, but I cannot give you a full answer except to say that I would expect it to contain a complex mixture of esters, as well as many more other types of molecules besides.
As to your method, it all seems sound in theory, but the problem is that potassium dichromate may well oxidise other components of the perfume apart from ethanol. For example, there are likely to be other alcohols present too, such as methanol, whereas in wine ethanol predominates. There is no easy way of getting round this, so when you carry out your calculations you will need to do this in terms of total alcohol content.
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Risk assessment
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updated: 30 March 2006
