Bunsen Burner

Parts and function

The Bunsen burner is the most frequently used heating device in IGCSE practical work. Its design is simple but each part serves a specific purpose:

Gas inlet: Connects to the laboratory gas supply via rubber tubing. A gas tap on the bench controls the flow.

Base: A heavy, flat base provides stability. The burner should always be placed on a heat-resistant mat.

Air hole and collar: A rotating collar covers or exposes the air hole. When closed, only gas enters the barrel (producing the yellow flame). When open, air mixes with the gas (producing the blue flame). The degree of opening controls the air-to-gas ratio.

Barrel (chimney): The vertical tube where gas and air mix before combustion at the top.

Flame types

Yellow (safety) flame — air hole closed

• Luminous, easily visible, yellow-orange colour
• Relatively cool (approximately 300 degrees C)
• Produced by incomplete combustion of the gas (insufficient air)
• The yellow colour comes from glowing carbon particles (soot)
• Used as the “parking” flame when the burner is on but not heating anything

Blue flame — air hole open

• Almost invisible, pale blue colour with an inner cone
• Much hotter (up to approximately 1500 degrees C at the hottest point)
• Produced by complete combustion of the gas (sufficient air)
• The hottest zone is just above the tip of the inner blue cone
• Used for all active heating

Roaring blue flame — air hole fully open

• The air hole is opened as wide as possible
• Produces a very hot, noisy flame
• Used for strong heating (e.g., heating crucibles, thermal decomposition)

Uses in IGCSE Chemistry

• Heating liquids in beakers (using a tripod and gauze)
• Heating solids in crucibles (using a pipe-clay triangle and tripod)
• Heating test tube contents (holding at 45 degrees, moving in and out of flame)
• Flame tests (heating nichrome wire in the blue flame)
• Thermal decomposition experiments
• Bending glass tubing (not commonly tested)

Safety

• Always light the match or lighter before turning on the gas
• Use the yellow safety flame when the burner is not actively heating
• Never leave a blue flame unattended (it is nearly invisible)
• Keep flammable substances (ethanol, paper, hair) away from the flame
• Tie back long hair and tuck in loose clothing
• Place on a heat-resistant mat
• Turn off the gas at the bench tap when finished, not just the burner