Why does the matchstick burn on rubbing it on the side of the matchbox?

A matchstick burns when it is rubbed against the rough surface on the side of the matchbox due to a chemical reaction that takes place on the matchstick's tip. This reaction is commonly known as combustion or burning.

Here's how the process works:

Ignition compound: The matchstick's head (also called the match head) contains a mixture of chemicals, commonly including potassium chlorate (oxidizing agent), sulfur, and a small amount of powdered glass (for friction). The combination of these chemicals creates an ignition compound.

Friction: When you strike the matchstick against the rough surface on the side of the matchbox, the friction generates heat, causing the ignition compound on the matchstick's tip to react with the heat.

Combustion: As the ignition compound reacts with the heat generated from friction, it undergoes a rapid chemical reaction, releasing energy in the form of heat and light. This reaction generates a high temperature, causing the surrounding wood of the matchstick to catch fire.

Self-sustaining flame: Once the wood catches fire, it releases volatile gases, such as vaporized hydrocarbons. These gases further feed the flame, allowing it to continue burning as long as there is enough oxygen available for the combustion process.

In summary, the matchstick burns when rubbed on the matchbox because the friction initiates a chemical reaction in the match head, leading to the production of heat and light, which ignites the wood, and the flame sustains itself by burning the volatile gases released from the wood.