With confinement, my son would like to do some home experiments for a class. So far, he has a good setup that seems sound for the electrolysis of water. A later part of the experiment would combine back the $\ce{O2}$ and $\ce{H2}$ to get back water vapour.
What amount of atmospheric pressure $\ce{H2}$ and $\ce{O2}$ can be safely combined, at home, without it turning to a fireball and/or a news event? From Googling, I found 12,749 joules per litre of hydrogen. What I'm asking is:
How does dissipating 12K joules look like in a plastic bucket? Is this a case of needing only gloves and eye protection, or does it need further protection? Will it be just some heat, just a small flame, or a McGyver-type explosion?
Also, will $\ce{H2}$ and $\ce{O2}$ at atmospheric conditions instantly react, or would this be a progressive reaction?