Help me recall this chemistry demonstration

Calling all chemical-science-type people,

I remember watching a demo in 8th grade chemistry wherein the teacher poured some liquid into a beaker that was about a quarter full of ordinary white sugar. Within seconds, an enormous black stalk grew out of the sugar/liquid mixture. It got so tall the teacher had to hold it with tongs to keep it from toppling over. I think it eventually reached a height of about a half meter.

What was the liquid, and what was the experiment meant to demonstrate?

Concentrated sulfuric acid. It is an exothermic dehydration reaction

Don’t EVER try it in a plastic container! Says one who liked to steal chemicals from his high school chem lab and play with them at home several decades ago. :eek:

Yes that’s it! What’s the purpose if adding a little water first? I do t remember that part.

I don’t recall that, but maybe pre-dissolving the sugar helps kick it off faster. Liquid-liquid reaction instead of liquid-solid.

I should have mentioned that some stuff isn’t all that soluble in concentrated sulfuric acid.

And, adding a little water will heat things up quickly.

But add acid to water, not the other way around. You don’t want to get splashed with hot sulfuric acid.

Just a cautionary note: be aware that the reaction gives off some acrid-smelling fumes, so do this in a well-ventilated place (or better yet, a fume hood). And have fun! :slight_smile: