← Chemistry Revision

Chemistry · Combustion

Bunsen Burner Lab.

Why does closing the air hole turn the flame yellow? Press play for a narrated explainer (about 1½ minutes, turn the sound up), then use the air-hole slider yourself.

open
Closed (little oxygen)Open (lots of oxygen)

Inside the flame · one methane molecule
Oxygen atoms per methane
carbon hydrogen oxygen

The hydrogen always ends up as water. Only the carbon's product changes, depending on how much oxygen is left for it.

Check you've got it

Flashcards this explains

Fuel + (excess) oxygen →Carbon dioxide + water
Fuel + (less) oxygen →Carbon monoxide, carbon + water
Colour of flame in complete combustionBlue
Colour of flame in incomplete combustionYellow (because of carbon/soot in the flame)
Combustion reactionFuel + oxygen makes energy and water

The last card leaves out carbon dioxide. When there's enough oxygen, burning a fuel makes carbon dioxide and water, as the first card says. Open the flashcards

Narration voice: Max, generated with ElevenLabs.