Practical investigations
Read our general notes on Risk Assessment
I am doing an investigation to determine ethanol content of wine based on chemical properties. I have few questions to ask:
1. What is the best method to determine and how can I check the accuracy of the method ?
2. How can I remove the red pigments in wine?
Igloo writes ...
The usual chemical method of determining ethanol content is to carry out a set of reactions involving the oxidation of ethanol to ethanoic acid using acidified dichromate(VI) ions.
First a solution of sodium dichromate(VI) is titrated with an acidified standard solution of iron(II) ammonium sulphate to ascertain its exact concentration.
Next an excess known volume of the sodium dichromate(VI) is added to a known volume of the wine together with dilute sulphuric acid, and the mixture is heated on a water bath for some time to allow the redox process to complete.
Finally the mixture is back-titrated with the iron(II) ammonium sulphate solution to find out the number of moles of dichromate(VI) ions remaining.
Further details of this technique can be found on our web site ( React FAQs on the analysis of wine).
The usual way of removing the colour in red wines is to use activated charcoal. Once again you will find details of how this can be used by reference to our React FAQs.
Always carry out a risk assessment and check with your teacher before starting any practical work.
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 April 2008
