I am trying to isolate and extract (mostly) hydrogen via a reaction. The reaction I was thinking of was aluminium and caustic soda, giving hydrogen gas, which I would collect in balloon i.e. The hydrogen inflates the balloon and I hold the mouth and take it off, thus having mostly hydrogen gas inside. From there I am a bit stumped at how I could store this hydrogen. I obviously can't just keep it in the balloon. Are there any alternatives that I could use/something air tight I could make? Are there any containers out there that I could possibly buy which would allow me to make this happen or are there better processess out there? all suggestion welcome, thanks! Note: I know I can just buy pure hydrogen, but where is the fun in that?