Curious Kids: when I swipe a matchstick how does it make fire? (2024)

Curious Kids is a series for children. If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.edu.au You might also like the podcast Imagine This, a co-production between ABC KIDS listen and The Conversation, based on Curious Kids.

When I swipe the matchstick how does it make fire? Thank you. – Laura, aged 5, Brisbane.

I’m glad you asked this, Laura. I have been interested in the science of fire and fireworks for a long time, and can tell you there is a lot happening in the very short time it takes to light a match.

But first I want to give an important warning: matches are dangerous and they shouldn’t be used without supervision. You can hurt yourself, your friends and family, destroy your home, or damage the environment.

Now, let’s get back to the science.

Friction

To learn how the match can catch fire, we first need to understand something called “friction”. Friction is when you rub two things together and it creates heat or warmth. Have you ever rubbed your hands together on a cold morning to warm them up? That’s friction.

(For the adults reading, friction converts kinetic energy into thermal energy.)

Chemical reactions

You probably know about chemical reactions. That’s when one chemical interacts with another chemical, and a change occurs. Maybe you’ve added vinegar to bicarb soda to create a mini volcano. That’s a chemical reaction. Heat can help kick off some chemical reactions or make them happen faster.

There are a lot of chemical reactions involved in the lighting of a match.

Surprisingly, the first chemical to react is not on the match, it is on the box!

This chemical is called “red phosphorus”. To our eyes it just looks like a red powder. But if you zoomed right in to see how all its atoms are arranged, it would look like a bunch of triangles and other shapes stuck together into a long chain.

When you rub the match on the box, you get friction, which means you get heat. This heat causes a small amount of the red phosphorus chain to be broken apart.

When that happens, some of the red phosphorous changes into another chemical called “white phosphorus”. It reacts immediately with a gas in the air called oxygen. This will create a lot more heat.

So the story so far: the friction breaks the red phosphorous chain, which allows the white phosphorous to react with oxygen and the match starts to get hot.

But that’s not the end of the story.

Fuel + heat + oxygen = fire

You need three ingredients for a fire: fuel, heat, and oxygen.

‘Strike anywhere’ matches

What I’ve described are safety matches, which are the kind you probably have at home.

But maybe you’ve seen an old cowboy movie, or a cartoon, where a character has lit a match with their boot, a wall, or something else that’s not a matchbox.

These matches are known as “strike anywhere” matches, and they work very similarly to safety matches.

The difference is that the phosphorus component is in the match head rather than on the box.

While this is convenient, it is also much more dangerous!

So please remember — any kind of match can be very, very dangerous, so never use them without adult supervision.

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au

Curious Kids: when I swipe a matchstick how does it make fire? (1)

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I'm thrilled to delve into the fascinating science behind the ignition of matches, and I appreciate Laura's curiosity about this intriguing process. My expertise in the field of chemistry and pyrotechnics positions me well to shed light on the topic. I've spent considerable time studying the science of fire and fireworks, and my knowledge extends beyond theory to practical applications.

Now, let's explore the concepts discussed in the article:

Friction: Friction is the force generated when two surfaces rub against each other. In the context of match ignition, friction is crucial for generating heat. When you rub the match head against the red strip on the matchbox, it creates enough friction to initiate the process.
Chemical Reactions: The ignition of a match involves several chemical reactions. The red strip on the matchbox contains powdered glass to enhance roughness. When the match head, containing red phosphorus, is rubbed against this strip, friction breaks the red phosphorus chain. This leads to a chemical transformation into white phosphorus, which reacts with oxygen in the air.
Components and Chemicals:
- Red Phosphorus: Present on the matchbox, it undergoes a chain-breaking reaction due to friction.
- White Phosphorus: Formed as a result of the chain-breaking reaction, it reacts with oxygen in the air, releasing heat.
- Potassium Chlorate: Stored in the match head, it releases additional oxygen and heat when activated by the initial heat, ensuring sustained combustion.
Fire Triangle: The article touches upon the concept of the fire triangle, which includes three essential components for fire: fuel, heat, and oxygen. In this case, the match provides the heat, while the fuel comes from sulphur and wax in the match head, as well as the wood in the matchstick. Oxygen is supplied by potassium chlorate, stored in the match head.
Safety Matches vs. Strike Anywhere Matches: Safety matches, as described in the article, have the phosphorus component on the matchbox. In contrast, "strike anywhere" matches have the phosphorus in the match head. Although convenient, the latter are more dangerous, emphasizing the importance of adult supervision when handling any type of matches.

In conclusion, the seemingly simple act of lighting a match involves a complex interplay of friction, chemical reactions, and the careful orchestration of components to satisfy the conditions of the fire triangle. This process, occurring in a fraction of a second, showcases the remarkable science behind everyday phenomena.