Organic unknowns: test-tube tests sim
Six unlabelled colourless liquids. Drag reagents onto the tubes, record every result, build a key that separates all six (results that look alike cannot split them), name them, then make an ester from the alcohol you found.
Organic chemistry: identifying alkanes, alkenes, alcohols, carboxylic acids and esters by test-tube tests · covers the GCSE, IGCSE, O-Level topic
What the sim shows
Each functional group gives its own test results. Alkenes (cyclohexene) decolourise orange-brown aqueous bromine, because bromine adds across the C=C double bond; alkanes (hexane) do not. Carboxylic acids (ethanoic acid) fizz with sodium carbonate, giving carbon dioxide that turns limewater milky, and turn damp universal indicator paper orange-red (pH about 2 to 3). Alcohols (ethanol) and alkenes turn warm acidified potassium manganate(VII) from purple to colourless: the alcohol is oxidised to a carboxylic acid. Sodium fizzes with water, alcohols and acids, giving hydrogen: steadily with ethanol, fast with water and with the acid (so sodium cannot tell those two apart). Burning: alkenes burn with a smokier flame than alkanes (more carbon for their hydrogen); ethanol burns with a clean blue flame; hexane and the ester burn alike, so smell is what separates them. Esters (ethyl ethanoate) smell sweet and fruity; you make one by warming an alcohol and a carboxylic acid with a few drops of concentrated sulfuric acid as a catalyst. Model limits: the six liquids are pure (the ethanoic acid is glacial); each result is the textbook one; long warming in acid can turn a little ester back into ethanol, so manganate(VII) may slowly fade with the ester (the textbook answer is that it stays purple); smells are wafted, never sniffed directly.
- Tubes 1–6: six colourless liquids
- Reagents: bromine water, manganate(VII), limewater, sodium carbonate, sodium
- Watch glass for burning; water bath for warming
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