why flames change color as the get hotter?
In: Chemistry
Flames emit black body radiation from soot and ash in the flame. Some fuels, like coal, have lots of carbon and ash particles, so they emit lots of black body radiation. Fuels like natural gas produce less soot and ash, so they tend to emit less black body radiation. Fuels like hydrogen produce no soot or ash, and as such, they emit even less black body radiation.
Burning fuels also emit radiation at specific frequencies related to the excited states of chemical species in the flame. In industry, this is called “luminosity”. This generally is the source for the blue color seen in natural gas and h2 flames.
For fuels like coal, the luminosity is a small part of the total radiation. For fuels like natural gas, the luminosity can be close to 50% of the radiation.
Latest Answers