Sulfuric acid and sugar classroom demonstration incident

Tom's classroom demonstration ~25 years prior (early 1990s). Students replicated unsupervised. Used to illustrate sulfuric acid as desiccant. Sucrose C12H22O11 → carbon + H2O.

An example I used to do — I don't do it in class anymore, I did it once but never again. If you take about one inch of table sugar and put it in a beaker about six inches tall — now do this in a hood. I did it in the classroom down the hall once, about twenty-five years ago. I told the students to set it up because I had done it before in the hood in the lab, and I decided I wanted to do it in the classroom. You take concentrated sulfuric acid and you pour about an inch of sulfuric acid on top of the sugar — about a fifty-fifty split. Anybody know the composition of sucrose? C12 H22 O11. If I take the H2Os out, what am I left with? Carbon. Sulfuric acid is a wonderful desiccant. It will strip all the H2Os out and leave carbon. When you pour the sulfuric acid in, the sugar turns a little gray, then blacker, forms kind of a black liquid, and then you see this big black mass grow up to about six inches high — triples its volume. It also gives off sulfurous acid fumes.