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Question
Hi,

Please could you explain why acetone evaporates 1st, then vinegar and then coke in a controlled temp of 28 degrees.

Thank you !

Answer
Hi Anita,

IT has to do with something called vapor pressure.  As you may already know there are solids, liquids and gases, these are three of the stages of matter.  When a liquid becomes solid, this is its freezing point and when a liquid becomes gaseous it is called its vapor pressure point. Of these liquids, Acetone has the lowest vapor pressure and as a result evaporates first.  Both Vinegar and Coke are complex mixtures both containing water.  Water's vapor pressure is higher than Acetones.  Vinegar contains acetic acid and water, for both to evaporate the vapor pressure needs to be at an equilibrium which allows the water and the acetic acid to evaporate at the same time.  Coke contains both water and lots of solids like sugar, carmel flavoring, colorants etc... That is also why you have a residue once the coke has fully evaporated.  There may also be a residue with vinegar too depending on type used.  Because Coke is a complex mixture, it takes a long time for it to fully evaporate.  Each component like water, phosphoric acid, corn sweetener all need to evaporate at different vapor pressures and this take a long time for the molecules to sort out.

I hope this helps.

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Ralph Salier-Hellendag

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Science Fair Judge for many years and experience with robotics, biology, chemistry, industrial processes, metalurgy and metal forming.

Experience

Science Fair Judge for many years and have helped several students get to state level competition. Most recently 2 of my students received state level awards and one went on to the nationals in Washington DC.

Education/Credentials
BA Archaeology - Anthropology
MA Business Anthropology

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