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Using carbon fuels

The Bunsen burner

The Bunsen burner is commonly used in school laboratories to heat chemicals. Its fuel is natural gas, which is almost pure methane, CH4. Methane is a hydrocarbon. So the Bunsen burner has an air hole that allows complete or incomplete combustion.

Air hole open

When the air hole is open, air is drawn into the chimney, where it mixes with the natural gas. This ensures complete combustion:

methane + oxygen    →    carbon dioxide + water

A very hot, blue flame is produced.

bunden burner with a flame - unburnt gas and air are at the centre of the flame

The hottest part of the flame is at the tip of the dark blue cone

Air hole closed

When the air hole is closed the natural gas can only mix with air at the mouth of the chimney. Incomplete combustion occurs as a result:

methane + oxygen    →    carbon monoxide + carbon + water

bunsen with a yellow flame

The yellow flame is often called the safety flame

A yellow flame is produced, which transfers less heat energy than the blue flame. The yellow flame is brighter than the blue flame because the specks of carbon glow when heated.

Back to Carbon chemistry index

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