Light the Bunsen Burner
The safe steps to a clean blue flame.
What this lesson covers
Why it matters
A Bunsen burner can give a gentle glow or a roaring blue flame hotter than boiling water. But light it in the wrong order and gas could escape before you are ready.
Predict first
Why do we bring a lighted match to the burner BEFORE turning on the gas?
Having the flame ready first means the gas lights immediately. If you turn on the gas first, unburnt gas escapes and can suddenly ignite in a big flare.
- So the flame is prettier
- So the gas lights the instant it comes out, instead of building up and causing a sudden flare — correct
- The order does not matter at all
- To cool the burner down first
What you do
Put the steps for safely lighting a Bunsen burner in the correct order.
Check yourself
Which Bunsen flame is the HOTTEST and best for heating?
With the air hole open, the gas mixes with plenty of air and burns completely, giving a hot blue non-luminous flame. This is the hottest flame and is used for heating.
When the air hole is CLOSED, the flame becomes yellow and luminous. Why?
A closed air hole starves the flame of air. The gas burns incompletely, forming tiny glowing carbon (soot) particles that glow yellow. This luminous flame is cooler and sooty.
Which is the safest reason to keep the air hole CLOSED when you are not actively heating?
The luminous yellow flame is bright and easy to spot, so a lit burner is not mistaken for being off. The near-invisible blue flame is used only while actually heating.
- The blue, non-luminous flame (air hole open) — correct
- The yellow, luminous flame (air hole closed)
- No flame at all
- A flame is never used for heating
- The gas burns completely with lots of air
- With little air the gas burns incompletely, leaving glowing soot that makes it yellow — correct
- The gas turns into water
- The burner is broken
- The yellow luminous flame is easy to see, so the burner is not left burning unnoticed — correct
- The blue flame gives out no heat at all
- A closed air hole makes the flame invisible
- It makes the gas last forever