How Is Black Fire Made?

TL;DW - it involves sacrificing a virginal chemistry student to the chemistry gods...

jk

Actually, this one's pretty brilliant. It's the distinction between emission and absorption spectra.

See, when the yellow light is produced (or emitted) - as shown around 1:00 in the video - it's because electrons are bouncing up and down within the atom (as shown via a Bohr model). That's an emission spectrum.

That requires energy. In the fire that energy comes from the chemical reaction of the ethanol (remember kids, no methanol) with oxygen...burning.

When the sodium vapor light is on, however, it's providing exactly the right amount of energy to excite those electrons. Which is then absorbed by the sodium atoms in the flame, leaving behind no light at all. That's an absorption spectrum.

And that's so cool...