2

Air is a mixture of O2, N2 etc. Which gases are ionised at STP, and is there a different level of ionisation for different gases?

user1504343
  • 21
  • Is not this a chemistry question? You could use the Chemistry SE for this one. – Karthik Apr 25 '19 at 11:27
  • 1
    @KV18 Sounds like a physics assignment. So only a hint: think of the Boltzmann factor. –  Apr 25 '19 at 11:49
  • @Pieter - how air might be ionized May also come into play. – Jon Custer Apr 25 '19 at 13:10
  • 1
    Everyone talks about air being ionised (such as an electrostatic ioniser) - I was idly wondering whether all the other gases were ionised at some point. I'm 71 - too old for a physics assignment!! – user1504343 Apr 26 '19 at 10:59

1 Answers1

0

The most common ionizations are of oxygen and nitrogen. Nitrogen ionizes first (at lower levels of energy input) and yields a deep blue color. Oxygen ionizes at a slightly higher energy level and adds a pinkish-white color to the plasma. Once the plasma heats up due to current flowing through it, it begins to emit a black-body spectrum and becomes white.

niels nielsen
  • 92,630
  • Are you sure about the order [Nitrogen 1st, then Oxygen], according to the Wikipedia Ionization_energies_of_the_elements_(data_page) Oxygen looses it's first electron at 1313.9 eV while Nitrogen holds on until 1402.3 eV – user263399 Nov 26 '21 at 06:16
  • @user263399, in practice you see the N2 lines first and at higher voltages and power levels you get the O2 lines. I do not know why this is so, but in the test setup I built for my thesis work in 1977 this was consistently true. – niels nielsen Nov 26 '21 at 17:11