What is the stochiometric equation of the sucrose and potassium chlorate reaction with sulfuric acid?

Question

I am researching this reaction for my chemistry assessment. Various sources I have dug up state different answers and opinions on what the stoichiometry is and what the products are, sometimes giving no answer at all.

In one source, sulfuric acid is a catalyst that speeds up the reaction while in another source, sulfuric acid is one of the reactants, and is therefore part of the stochiometry. The final products also vary from source to source, and include pure carbon or potassium chloride in addition to carbon dioxide and water.

Can anyone clarify the subject for me?

Answer 1

In this paper [Sugar Dehydration without Sulfuric Acid: No More Choking in the Classroom! T.P. Silverstein and Y. Zhang. J. Chem. Ed. 75 (6) 748-749 (1998)], the authors outline two reactions involving sucrose and sulfuric acid. The first one does not include $\ce{KClO3}$ and utilizes a significant amount of $\ce{H2SO4}$ in order to fuel the dehydration of sucrose: this is not the reaction you're interested in.

The second reaction detailed herein makes use of a very small amount of sulfuric acid to start the reaction (a drop is the commonly-cited amount): the sucrose is oxidized by $\ce{KClO3}$. This is the reaction you want to examine.

The authors give the reaction stoichiometry as $$\ce{C12H22O11(s) + 8KClO3(s) \xrightarrow{H2SO4} 12CO2(g) + 11H2O(l) + 8KCl(s) + heat}$$

They note that the fumes from the reaction contain $\ce{Cl2, ClO}$, and $\ce{ClO2}$, but the amounts are not quantified. I suspect (but don't know for sure) that the amounts are finite but negligible. And even with the scant amount of sulfuric acid used here, I think you're safe going with the reaction as presented above.