#Scrap-Science video of the #Kolbe #electrolysis of slightly acidified sodium acetate #materials to ethane (diluted with carbon dioxide) via free methyl radicals in a U-tube, requiring a platinum anode to hinder oxygen generation
on 02026-04-27#ScrapScience #video on #bootstrapping HNO₃ #materials from KNO₃ using a terracotta flowerpot as an #electrolysis membrane with the drainage hole plugged with silicone, incorrectly described as a “semipermeable membrane”, in an HDPE container made from cutting the bottom off a plastic milk bottle. Copper cathode made from thick wire, graphite anode made from some round graphite bars. 100g KNO₃, unknown quantity of water (maybe 500mℓ), some distilled water added to the anode chamber. Initially he gets 90mA at 7.5V (=80Ω), but pretty soon that rises to 630mA (≈12Ω), and he limited the current to 1.02A. No hydrogen is generated at the cathode, surprising him, but he says it’s because the nitrate ions are reduced to ammonium. After about a day the graphite anode has been completely eaten, which makes me think it wasn’t really graphite, but like carbon arc gouging electrodes or something. The cathode compartment ended up being very basic and smelling very strongly of ammonia, so he made ammonia too. He says his crude titration (not shown) tests the acid at 0.7 molar, which apparently isn’t enough to attack copper, so he boils it with some copper in it, eventually dissolving the copper after boiling it down 4×. While this method does seem to work, it seems a little bit like a method of making an engine starting with only a car — the cheapest way to get KNO₃ is by neutralizing HNO₃ with KOH. He also thinks it “isn’t good enough to be practical” because of how dilute the product is.
on 02024-06-25