# What chemical reactions could ancient people use to propel projectiles? [closed]

Are there reactions other than burning of gunpowder that ancient people could perform that would produce gas from non gaseous substances, so that it could have been used for propulsion of projectiles had they thought of it? An example would be CaO + H2O reaction, as upon mixing in a closed container this mixture would pressurize the container, and at some pressure the cord tying the projectile to the chamber would rip and projectile would be propelled

• How would those folks even know about pressure in the first place? It was only a few hundred years ago that people realized that the atmosphere had weight.
– Ed V
Apr 9, 2020 at 17:25
• @EdV you are right, but you don't need to know what is pressure to use it!
– G M
Apr 9, 2020 at 17:28
• @GM But why even have the idea of pressurizing some container and using it to propel something? There was Greek fire, too, and the Greeks were very intelligent, but they apparently did not invent rockets. Also, Hero’s engine demonstrated the use of steam, though they probably did not realize what steam was.
– Ed V
Apr 9, 2020 at 17:31
• Guess I missed the part where the OP’s question started with “Are there reactions other than burning of gunpowder”. Of course, there are actual baking soda mines, burnt wine and the white cliffs of Dover, but not much to go on. Maybe we do not hear of ancient rockets and cannons because their genius inventors were early winners of what we now call the Darwin Awards! ;-)
– Ed V
Apr 9, 2020 at 20:10
• @MathewMahindaratne you'd be surprised. I've see MacGyver DVD sets sold in European countries. Hollywood's reach is far and wide. Apr 10, 2020 at 16:25

The answer depends on what do you mean for ancient people. There are a lot of reactions that could produce gas for ejecting projectiles. The most common was the mixture of sulphur, potassium nitrate $$\ce{KNO3}$$ and carbon that is known as gun powder and has been reported to be used since the IX century in China.

If you want some less efficient and not used reaction, you could think of using methane explosion extracted from some swamp. Or some reaction between calcium carbonate and acetic acid. Like this one between sodium hydrogen carbonate:

$$\ce{NaHCO3 + CH3COOH -> NaCH3COO + CO2 + H2O}$$

One of the earliest use of Black Powder was crude large-bore handheld guns (early China). And, actually much more, to quote a source:

Other Song military applications of gunpowder included primitive hand grenades, poisonous gas shells, flamethrowers and landmines. The first artillery pieces were rocket tubes made from hollow bamboo shoots, but these were soon upgraded to cast metal

Cannon tube + water in a sealed container + cannonball. Add heat. How far the cannonball goes depends in part on the strength of the container.

• I suppose you are referring to the steam cannon. Could you please elaborate? Apr 10, 2020 at 20:44