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Lesson · Grade 10 · Science

The Fire Triangle: Heat, Fuel and Oxygen

  • Grade 10
  • Science
  • 1 min 53 s
  • British Columbia
  • BC10-SC-29

A labelled triangle builds up around a flame, one side at a time: fuel, heat (with the ignition temperature, roughly 200 to 250 °C for paper) and oxygen (about 21% of air). Combustion is shown as a chemical reaction whose heat keeps the fire going. Each way of putting a fire out then slides one side away so the flame dies: water removes heat; a lid, blanket or CO₂ extinguisher removes oxygen; firebreaks and First Peoples' controlled burns remove fuel. The video also shows that more oxygen makes fire burn faster and why water must never go on a grease fire, then ends on a one-line recap.

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In one sentence

The question this lesson answers

What does a fire need to keep burning?

First, fuel: anything that can burn, like wood, paper or natural gas.

Transcript

What the lesson says

What does a fire need to keep burning?

First, fuel: anything that can burn, like wood, paper or natural gas.

Second, heat: enough to bring the fuel to its ignition temperature.

The ignition, or kindling, temperature is the lowest temperature at which a material catches fire.

For paper, that is roughly 200 to 250 degrees Celsius.

Third, oxygen. Air is about 21 percent oxygen.

Burning, or combustion, is a chemical reaction of fuel with oxygen that releases heat and light.

That heat ignites more fuel, so the fire keeps going.

Together, heat, fuel and oxygen make the fire triangle: take away any side, and the fire goes out.

Water removes heat, cooling the fuel below its ignition temperature.

To cut off the oxygen, use a lid, a fire blanket or a carbon dioxide extinguisher.

A firebreak, a strip cleared of plants, takes away fuel from a forest fire.

Many First Peoples have long used small, controlled burns to clear away dry fuel.

Air is about 21 percent oxygen. With more oxygen, fire burns much faster.

But water is not safe on every fire: never use it on a grease fire.

Water sinks under the hot oil, flashes to steam and throws burning oil out.

Instead, turn off the stove and slide a lid on to cut off the oxygen.

Fire needs heat, fuel and oxygen; take away any one, and it goes out.

Curriculum

Where this fits

British Columbia, Grade 10

Science 10, Chemistry: practical applications and implications of chemical processes, including First Peoples knowledgeBC10-SC-29

Previous: Why You Must Never Mix CleanersNext: Polymers: Long Chains of Repeating Units

The outcomes and strands follow the British Columbia curriculum.

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