I got my film developing chemistry mixed up last night (Kodak D-76, and Kodak Fixer). I have four exposed rolls in the fridge, so it’s time to start processing them.
I keep my D-76 in small (591mL/20oz) pop bottles; this way I only ever have one partially full bottle, and as long as it’s at least half full, it’s easy to squeeze the air out. Last time I did this, I found the pop bottles to keep the chemistry fresh for a long time; D-76 tends to turn yellow/brown when it’s too old, but in these bottles it was clear as water even a full year after being mixed. I also don’t bother with dark bottles, my chemistry is kept in a dark room (the darkroom) and I’m the only person using it, so the lights are rarely on (and the small bottles go in a cabinet, so that’s dark even when the lights are on).
I’m not saying that what I do is the correct way of doing things, or that it’ll even work for you, but this is what I do, and it works for me, but your milage may vary.