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Before a combustible substance can catch fire and burn, it must be heated to a certain
minimum temperature by supplying heat from outside. It will not catch fire as long as its
temperature is lower than its ignition temperature.
For example, the ignition temperature of paper is 233 C. So a paper should be heated
0
to 233 C to start burning. To burn a paper we generally use a matchstick which
0
supplies heat to raise the temperature of the paper to kits ignition temperature.
Similarly, a match stick does not catch fire and burn on its own at room temperature
because the ignition temperature of the match stick is much higher than the room
temperature. It can be lighted by rubbing it on the rough surface provided on the side
of the matchbox.
*Ignition temperature of different substances is different.
i. Some substances have a low ignition
temperature. For example paper, dry grass, etc.
Those substances which have very low ignition temperature and can easily
catch fire are called inflammable substances.
For example LPG, Kerosene, etc.

Some substances have a high ignition temperature. They can catch fire only on string
heating. For example Coal, Charcoal, Log of wood, etc.

*A paper cup containing water if shown over fire does not burn, whereas an empty
paper cup burns. This can be explained as, when we heat the empty paper cup, the
ignition temperature of the paper cup is reached very quickly and it starts burning.

But when we heat the paper containing water, then the heat supplied to the paper is
transferred to the water inside it by conduction. Due to the continuous transfer of
heat, the paper cup does not get heated too much to reach its ignition temperature.

The History of Matchstick
More than a thousand years ago small pieces of pinewood dipped in sulphur were
used as matches in ancient Egypt. The modern safety match was developed 200
hundred years ago.
A mixture of antimony trisulphide, potassium
chlorate, and white phosphorus with some glue
and starch was applied on the head of a match
made up of suitable wood. When struck against a
rough surface, white phosphorus got ignited due
to the heat of friction. This started the combustion
of the match. However, white phosphorus proved
to be dangerous both for the workers involved in
the manufacturing of the matches and for the
users.
These days the head of the safety match contains only antimony trisulphide and
potassium chlorate. The rubbing surface has powdered glass and a little red
phosphorus. When the match is struck against the rubbing surface, some red
phosphorus gets converted into white phosphorus. This immediately reacts with
potassium chlorate in the match struck head to produce enough heat to ignite antimony

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