To which state of matter does the flame belong to?

Question

I had this question from the day(9 years old, now 16) that i learned about states of matter. I have asked so many of my teachers some of them told me gas some as plasma etc. can anyone answer my question? Recently I've learnt that plasma state is obtained when all the electrons from the atom are removed. Obviously its present in sun due to high temperature.

Answer 1

I would differ from Xiao because I wouldn't say that a gas and a plasma were the same state of matter, though this is largely terminology.

However this doesn't matter because a flame is not a plasma but a gas phase reaction. So it's just a gas. You mention the Sun, but although the Sun is mostly plasma it isn't a flame in any of the common uses of the word.

Have a look at Confused about fire? for more info.

Answer 2

Flames always contain gas, but often include solid particles as well. Solid carbon particles are responsible for the luminous yellow flames of candles and wood fires.

The fraction of the atoms which are ionized (plasma vs gas) is determined by the Saha-Langmuir equation (see J. Appl. Phys. 39, 338 (1968)). There is an equilibrium between ionized and bound states. Give the ionization energy of an element in the flame, temperature, and pressure, the fraction ionized can be determined. At the temperature of common flames, the ionized fraction is low. Alkali metals such as sodium, potassium, etc., which have low ionization energies would have the highest ionized fraction.

Flames can contain molecular radicals such as CH, CC and OH, the emission spectra of which are responsible for the blue color often seen in flames such as hydrocarbon flames.

Answer 3

Gas and plasma are the same state of matter. So flame = gas = plasma.

Gas and plasma are the same state of matter (meaning belongs to the same phase) since they have the same symmetry. For the same reason, water and vapor are the same state of matter (belongs to the same phase).