I'm looking for a chemical reaction in order produce about 5 liter of harmless gas.

The goal is to start with something that takes as little volume as possible to start with, and reacts to fill up a bag, and also not producing too much heat to not harm the bag.

Every answer is appreciated!


closed as too broad by Todd Minehardt, airhuff, Mithoron, paracetamol, pentavalentcarbon Dec 16 '17 at 18:32

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I'd go with carbon dioxide $\ce{CO2}$ as a rather convenient gas which is non-flammable and doesn't require special equipment or exothermic reaction to synthesize. Common ways of obtaining $\ce{CO2}$ gas are:

  • Dry ice + ambient temperature above $\pu{−78.5 ^\circ C}$;
  • Carbonate + acid. These reactions rarely have significant thermal effect. One of the best mixture would be sodium bicarbonate + citric acid + water. Assuming dissolving of citric acid is endothermic and takes some time, prepare the solution of citric acid beforehand.

$\ce{O2}$ and $\ce{H2}$ are rather dangerous in terms of flammability, also common synthetic methods require exothermic reactions.

$\ce{N2}$ is inert, but not easy to come by; the most effective way of obtaining nitrogen would be thermal decomposition of azides $\ce{M^IN3}$ and ammonium nitrite $\ce{NH4NO2}$.

  • 1
    $\begingroup$ There used to be little ‘bomb bags’ available. Sealed bags containing sodium hydrogencarbonate and a smaller internal bag with acetic acid. You broke the inner bag and after some time the pressure built up inside would make the bag explode. $\endgroup$ – Jan Dec 16 '17 at 6:07
  • $\begingroup$ @Jan Interesting. Must be local though; when I was a kid calcium carbide and some water in a tightly closed bottle used to be a trend:) $\endgroup$ – andselisk Dec 16 '17 at 6:12

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