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When sulphuric acid is added to sugar it turns black what is the reason?

Sugar (a carbohydrate) is dehydrated with concentrated sulfuric acid. Since a carbohydrate was considered just hydrated carbon, if  the water is removed, carbon would be left over. The acid rips the water out of the sugar and the heat generated by this reaction causes the water to turn to steam. A black mass of carbon is produced.

Experiment:

 1. Place the sugar into a beaker .
 2. Add the sulphuric acid to the beaker.
 3. Stir it briefly.
           The sugar turns yellow and then red brown. After about one and a half minute the mixture changes color to black and a spongy mass of carbon grows well above the top of the cylinder. The formation of a carbon column is accompanied by the release of heat and evolution of vapor.


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