Practical investigations
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For my investigation on vinegar my aim was to work out the percentage acidity of both distilled and red wine vinegar. However, I don't know how to calculate the mass of vinegar. Could you please help?
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Igloo writes ..........
By “mass of vinegar” I assume that you are referring to the percentage by mass of acids in the vinegar.
The problem is that vinegar contains a complex variety of different acids, so the convention is to choose one of these and allow it to represent all the others. The acid normally chosen is the most abundant one, the one which gives vinegar its characteristic smell, i.e. ethanoic (acetic) acid.
I assume that you have carried out titrations and that you are able to calculate the total concentration of acids within the vinegar in mol dm-3.
This value needs to be multiplied by the molar mass of ethanoic acid (60) to convert the concentration into grams dm-3.
If this answer is then divided by ten, you will have found the number of grams of ethanoic acid present in 100 cm3, and this value is taken to be the percentage by mass of the acids present in the vinegar.
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updated: 13 April 2008
