Classroom Volcano

[MTbowels]

I was thinking back to my schooldays a few days ago and I recall a science teacher creating a volcano out of one or more powders in a metal tray by igniting the stuff with a match. Does anyone know what the stuff was?

[theprof]

You've not said a lot about the powder, but I'm willing to bet it was orange in colour. The demonstration uses ammonium dichromate and the usual method was to create a volcano shape out of the powder and bung a lit match into the peak of the powder.
The powder burns slowly at first but lots of sparks will shoot up after a few seconds and the dichromate turns into flaky, green, chromium (ii) oxide ash. Steam and nitrogen are also produced in the process.
This is an example of exothermic decomposition and was often done on the teachers desk in front of students. Nowadays, it's necessary to use a fume cupboard, wear goggles and have a powder or CO2 extinguisher nearby thanks to the HSE because all chromium containing salts are toxic. They are not so easy to obtain nowadays due to some nefarious uses.
The demonstration can also be done in a lightly plugged, glass flask too which is a little safer if you use the right equipment.
There are other chemical mixtures that will do the same, but nothing so spectacular as the dichromate one. The experiment was on the CSE and "O" level chemistry curriculum of many examining boards for quite a few years.

[Buenchico]

Even before reading TheProf's answer, your question transported me back to my schooldays, when there was a wonderful chemist's shop in Ipswich. It functioned not only as a pharmacy but, very unusually, lived up to the 'chemist' part of its description by selling chemicals of the types used in science labs. I often purchased ammonium dichromate there, in order to have fun heating it.

The technique that my mates and I used though wasn't usually the 'volcano' one. We preferred to heat a small quantity in a test tube, waiting for the dramatic moment when a chemical reaction took place, sending the resultant materials flying up (and often out of) the test tube.

A few years later we moved onto far more interesting stuff although, strangely, my mother never seemed to be very happy about having nitro-glycerine stored in her fridge ;-)

Here's your volcano though:

[theprof]

Ah those were the days Chris. I had a similar teenage years.

I used to buy Muriatic Acid (aka Hydrochloric Acid) at full strength from an ironmongers by the pint along with copper sulphate by the pound that was sold from paper sacks out the back. Sulphuric acid as "acquired" from old car batteries down the local scrapyard with the watchman turning a blind eye.

I too had access to an old fashioned chemist who used to sell me saltpetre ( potassium nitrate) by the pound with no questions asked for my gunpowder experiments. Sulphur was obtained at the garden shop (no garden centres in those days) in the form of "flowers of sulphur", an old but effective cure for fungal diseases in the garden. Charcoal was readily obtainable at the chemist too in the form of tablets for flatulence!

I remember I once asked the chemist if he get me sodium potassium tartrate (Rochelle Salt ), a double-salt ( don't ask!) as I wanted to make Fehling's Solution No 2. He got me the stuff by the following week.

I had lots of fun with waterglass ( sodium silicate solution) that was purchasable in Boots and was used for many years to preserve fresh eggs.

In those days, garden shops freely sold arsenic salts for the destruction of rodents.

[beso]

My son made a Potassium Permanganate/glycerol "volcano" for a science project in primary school. It was talked about at the school for many years afterwards.

https://sciencenotes.org/potassium-permanganate-volcano/#:~:text=The%20potassium%20permanganate%20volcano%20is,resembling%20lava%2C%20and%20colored%20ash.

Before 9/11 he made a lot of different pyrotechnical materials from readily available materials. Magnesium powder from old VW gearboxes was a staple.

It was always a fine line between making a beautiful fountain or rocket and an explosion.

Once we even made Potassium Chlorate.