I have a half gallon sitting around. Anything neat I can do with it?
i would definitely drink it if i were you
Mix it with sugar and it will make a GIANT worm of carbon that just keeps shooting out. It looks like a turd... smells like one, too! (The reaction releases hydrogen sulfide gas.)
drink it!!(JUST KIDDING!!)you could get some zinc and make hydrogenor do this https://www.instructables.com/id/Make-a-Test-Tube-Thunderstorm
Mix it with a nitrate and use the Nitric acid
if you have that white powder in your lawn just spray it on and the powder will be gone.
Sell it to some one who does jewellery or metal work as a pickling solution to clean their work.
Is it concentrated?
You could get some roofing-lead (flashing) and make batteries with it, half a gallon should be good for a lot of power.