Why are flames sometimes blue and sometimes yellow?
The color of a flame depends on the material being burned. There are lots of fuels that will produce blue flames when burned; the most commonly available one in the household is natural gas. You can look at the flame on the stovetop (if your stove uses natural gas) or furnace to see a pretty blue flame (don’t get too close! These are hot!). Natural gas, or any other pure hydrocarbon such as butane or propane will burn a light blue. copper compounds + chlorine producer copper acetoarsenite (Paris Green), Cu3As2O3Cu(C2H3O2)2 = blue copper (I) chloride, CuCl = turquoise blue The color of a fire won’t depend on what you use to start it, however, just what is burning at the time. Many ordinary flames (for example, burning wood or paper or candles) are yellow because of the presence of a small amount of sodium atoms in the fuel. Sodium atoms glow yellow very brightly when they are heated; yellow light is their very favorite color to emit (this particular shade of yellow is called the “sodium
