Australia's Science Forum

I have a couple of students wanting to make smoke bombs using potassium nitrate and I'm not sure what else, to be used for a chemistry classroom presentation and possibly shown to local primary schools. Can anyone help with information on how to do it, whether we should be doing it, and any precautions that should be taken in the making and using?

thanks
Cecilia

The internet will give you recipes for smoke bombs. Best to run off an MSDS for potassium nitrate before you decide. The MSDS put out by JT Baker is a good one. Once you have that info then it is up to the head science teacher to decide whether the students should be allowed to cook this stuff up. The supervising teacher will need to take all responsibility for any mishaps or accidents.
Lyn.

12g potassium nitrate
8g white sugar

Place dry ingredients in a beaker and using hot plate, heat with stirring until molten and caramelized. Beaker tongs are recommended. Do not heat ingredients with a naked flame/Bunsen. Pour/scrape into evaporating dish or a paper cup. Allow to set. Take outside and place cup on heat-proof mat. After removing flammable materials from the immediate area, squirt some metho in dish and ignite with match. Stand back.

Fumes are toxic; do not ignite indoors or on a windy day. Avoid breathing fumes. Precaution: Have fire extinguisher handy.

There is a website called chemistry.about.com which has a number of entertaining experiments including smoke bombs, coloured smoke bombs, pyrotechnics etc. Check it out.
Lyn.

Just make sure you let the local fire men know what you are up to. They do let off a lot of smoke. We did this for our year 12 break up a couple of years ago. Just our of kindness let the approapriate people know whats going on.
KIMMY