Fuel, oxygen and heat
Take things away one at a time and see when the burning stops.
What does burning need?
A piece of wood is a combustible substance. The air around it has oxygen. It still does not burn on its own.
How many things must come together for wood to burn?
What this lesson covers
The idea
Combustion needs three things: a combustible substance (fuel), oxygen, and heat that allows the fuel to reach its ignition temperature.
What does burning need?
A piece of wood is a combustible substance. The air around it has oxygen. It still does not burn on its own.
How many things must come together for wood to burn?
- One
- Two
- Three
Set it up and press Go
Choose the fuel, the air and the heat. Guess what will happen, then press Go. Then take away one thing at a time.
Three requirements
It burned only when all three were there. When any one of them was missing, the wood did not keep burning.
For combustion there are three requirements: a combustible substance (fuel), oxygen, and heat that allows the fuel to reach its ignition temperature.
- Fuel | Oxygen | Heat | Result
- wood | open air | heater on | burns
- stone | open air | heater on | does not burn
- wood | jar over it | heater on | goes out
- wood | open air | heater off | does not burn
Notes
For combustion there are three requirements: a combustible substance (fuel), oxygen, and heat that allows the fuel to reach its ignition temperature.
Check yourself
A log lies in the open air. The air has oxygen, and wood is a fuel. Why does the log not burn?
A stone is heated in the open air. It gets hot but does not burn. Which requirement is missing?
Wood has a fuel, oxygen and heat. Someone takes away the oxygen and the heat, but keeps the wood. How many of the three requirements are still there?
Answer: 1
One: the wood, which is the fuel. Without oxygen and heat it will not burn.
Which set lets a piece of wood burn?
- It is not hot enough to catch fire — correct. Yes! It needs heat to reach its ignition temperature.
- Wood is not a fuel, so it can never burn. Wood is a combustible substance. It burns when it gets heat.
- There is too much air around it to burn. The air has the oxygen that burning needs. The log is missing heat.
- Oxygen. There is oxygen in the open air.
- Fuel — correct. Yes! A stone is not a combustible substance.
- Heat. The stone got hot, so there was heat.
- Wood and oxygen, but no heat. It needs heat to reach its ignition temperature.
- Wood and heat, but no oxygen. Burning needs oxygen. Without it, the flame goes out.
- Wood, oxygen and heat — correct. Yes! All three requirements are there.