Practical investigations
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I am starting my vinegar investigation and am confused about the distillation. Firstly, I started with a round-bottomed flask and attached a stillhead and inserted a screwcap adaptor into this and then a thermometer. I added the Leibig condenser with rubber tubing. Then it became difficult at the final stage.
As I need to collect the distillate over ice, I’m not sure what to use. Should I add a receiver adaptor leading into another round bottomed flask with this flas submerged in the ice bath? Or is there something else I could use so I do not lose the distillate to evaporation?
Once I have this set up, do I titrate the distilled vinegar straight away or do I need to dilute this with distilled water? Could I do exactly the same with malt vinegar or do I need to decolourize this first?
Is there a precise amount of vinegar I should add to the flask to begin with or should I just guess how much will give me enough product and also leave me with enough non-volatile liquid to titrate? What temperature should I be aware of on the thermometer and is it possible for me to seal both the products and reactants for titration on a different day?
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Igloo writes ...
So many questions! I’ll go through them one by one.
Your distillation set-up seems fine to me. You must attach a “receiver adaptor” between the end of the condenser and the round-bottom flask submerged in the ice-bath, because the whole apparatus must not be air-tight. Otherwise the expansions occurring will cause an explosion. Providing that the round-bottom flask is well submerged in the ice bath, you will probably lose little of the ethanoic acid via evaporation.
There is no need to dilute the vinegar first before carrying out the distillation.
There is no need to decolourise the malt vinegar or any other coloured vinegar you might be using. The coloured components will remain in the boiling flask.
You need to measure out a precise volume of vinegar to start with so that when you come to titrate portions of your distillate you can scale up and find out the concentration of volatile acids in the original vinegar. Perhaps using about 100 cm3 would be appropriate – it all depends on the capacity of your flasks.
Carry on distilling until the liquid drops emerging from the end of the condenser are no longer acidic. This should coincide with a temperature of about 100°C on your thermometer.
All samples can be sealed for analysis on the following day. They won’t go off !
Risk assessment
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updated: 21 February 2008
