As rocket Science and Space Exploration is becoming more and more popular, I'm currently running some numbers, whether it would be possible to build a rocket engine for showing at schools or universities, without the need to be fit for flight.
The idea is to have a "normal" chemical combustion engine, but as performance is not a optimization criterion, but safety and availability for amateurs is I still search for a good fuel: The different oxidizers used in rocket motors are either cryogenic(LOX) or highly corrosive (Hydratzine and other Hypergolic Propellants), toxic and cancerous - nothing one would like to handle and which is cheap and easy to buy...
Is there any option for an oxidizer to combine with gasoline or ethanol as fuel, or a different combination of fuel and oxidizer? They should both be liquid (as pumps for liquids are available) and react strongly enough to build up the pressure in the chamber, but be individually safe enough to be handled without needing to consult a doctor if you accidentally spill a bit of it. I know that for an oxidizer this is a bit contradicting requirements, but maybe there is a good candidate.