Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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sulphuric acid : H2SO4
acetic anhydride : (CH3CO)2O
Class:
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elem=C,S
organic
Summary:
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Sulphuric acid and acetic anhydride react with each other. This reaction is
very violent. The final product is a very viscous colorless liquid. The main
constituent of this liquid is acetyl sulfate or acetyl bisulfate.
Description:
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Take approximately 1 ml of acetic anhydride and add a few drops of concentrated
(96%) sulphuric acid to this liquid: A very violent reaction occurs, in which a
lot of heat is produced and a strong crackling noise. This reaction is rather
scary! When the test tube is swirled carefully, then the liquids perfectly mix,
a single-phase system is formed.
Add more drops of sulphuric acid: Again a violent reaction occurs, but the more
drops of acid are added, the less violent the reaction is. At a certain point,
no more crackling noise is observed and the liquid becomes very viscous, like
syrup. The liquid has a smell of acetic acid/acetic anhydride.
Remark: The reaction, occurring here is said to be the following:
AC2O + H2SO4 --> AcHSO4 + AcOH
When more Ac2O is added: Ac2O + AcHSO4 <--> Ac2SO4 + AcOH
Here Ac stands for the acetyl group: CH3C(=O)-