I'm looking for a spontaneous reaction involving readily available (and cheap) compounds that form a very large volume of gas. Basically I'm looking for a sodium bicarb/acetic acid type reaction, but one that would release 3-4+ moles of gas/cycle. Either liquid/liquid or solid/liquid reactions would work, as both are easy to isolate from each other for long enough to toss the bottle a safe distance.
Thanks,
Nick