So it appears that making a plaster-of-paris model volcano for the science fair is just as popular today as it was when I was a kid. The difference is that, whereas nowdays kids use a wimpy mixture of baking soda and vinegar, we (ca. 1972) used used a chemical that, when ignited with a match, sparked and smoked and produced such a voluminous amount of ash that it appeared to be flowing lava. The first time I witnessed such a demonstration, I made my parents write down the name of the chemical so that I could make my own volcano. They never bought me any of that chemical (probably a good thing). Over the intervening years, I’ve half-heartedly searched the internet trying to recall the name of this magic chemical but have always come up empty. Now I’m a parent myself and my kid is thinking of recreating this classic. I don’t know how wise it would be to use pyrotechnics at a public school these days but I wanted to at least show him this fabulous display. Any chemists here have any idea what I’m looking for? I think it was green, if that helps.
Yep, that looks like it. Thanks!
Ammonium dichromate certainly provides more impressive results than Baking Soda and Vinegar, but it’s hardly more “realistic”, per the title of your post.
Should you be looking for something realistic:
http://nagt.org/files/nagt/jge/abstracts/Harpp-1_v53n2p173.pdf
By the time I graduated, the Cleveland school science fairs had a list of prohibitions longer than your arm. Among other things, your experiment couldn’t involve any living organism (not even plants), nor any flammable or reactive material, nor any liquid other than water, and your display at the science fair couldn’t even involve water, nor anything that plugged into wall power. Fortunately most of my experiments involved (battery-powered) electronics or robotics, so I was able to still do interesting things, but it pretty much killed several whole fields of perfectly good science.