# “Carbon snakes” - what physico-chemical process causes the exothermic response?

Making a "carbon snake" requires the mixing of strong sulphuric acid with sugar, as explained in this about.chemistry webpage - the reaction causes rapid dehydration of the sugar and produces steam in the process, which expands and forms the 'carbon snake', following the incomplete chemical reaction:

$\ce{C12H22O11 + H2SO4 → 12C + 11H2O}$ + mixture of excess unreacted water, sulfur dioxide and acid (and presumably a bundle of other chemicals)

My question is, what physical/chemical processes cause this rapid dehydration and exothermic reaction?

• Too busy to leave an answer but check this document out: ncsu.edu/project/chemistrydemos/Thermochem/DehydrationSugar.pdf – LordStryker Sep 24 '14 at 13:34
• Your equation is not balanced; you did not account for where the sulfur in sulfuric acid went. Some of the sulfur is oxidized into sulfur dioxide if I remember correctly. – Dissenter Sep 24 '14 at 13:34
• @Dissenter yes, I saw that too (that's what I get for copying that formula from the website - clarified it as an incomplete generalised formula) – user8016 Sep 24 '14 at 13:38
• does any one knows the ingridients of the commercial snakes – P.A.M Sep 28 '17 at 14:16

$\ce{C_mH_{2n}O_n -> m C + n H2O}$