Ignition Temperature

We already know about Combustion

In simpler terms, we call it burning

Scientifically, it is a rapid chemical combination of a substance with oxygen. This combination results in the production of heat and light

But, to initiate combustion some essential conditions are required

First, we need a substance that will combust. We call this substance Fuel

Second requirement to combust the fuel is oxygen

The third essential condition needed for combustion is Heat

These three are mandatory requirements to start combustion

But combustion does not start with the supply of a random amount of heat

To initiate combustion, this supplied heat has to raise the temperature of substance to a certain level

Let’s observe a scenario to understand this concept

A candle does not burn when kept at room temperature

This means that temperature level at which it burns has not been achieved

But when we heat it using a matchstick, it burns

So its temperature has increased beyond the temperature level at which it burns

We call this temperature level above which candle burns as ignition temperature of candle

So a candle will not burn if its temperature is less than its ignition temperature

It will burn as soon as its temperature goes above ignition temperature

We define ignition temperature of a substance as the lowest temperature at which it will burn

It is very important for a substance to reach its ignition temperature to combust

We can see this by performing an activity

We are taking two paper cups and we put 50ml of water in one of the cups

Let’s start heating both the cups with candles

We observe that empty paper cup has started burning

Whereas the paper cup with water yet not started burning

This is because paper reached its Ignition temperature only in case of dry paper cup

As the dry paper cup starts to burn earlier, it means its has reached its ignition temperature

While the cup with water does not reach its ignition temperature though we are supplying heat continuously

This is because the supplied heat is transferred to the water in the cup instead of heating the paper

Thus, the paper does not attain its ignition temperature and hence, fails to catch fire

On the basis of this activity, we can say that combustion occurs only after temperature rises to ignition temperature

So it is quite an important property to initiate combustion of any substance

Different substances have different ignition temperature

We can see this by looking at ignition temperatures of Kerosene and Wood

Kerosene catches fire very easily. You can burn it by using the heat produced by matchstick

But to burn wood, heat of a matchstick is not enough

Wood requires much more heat to ignite

This higher heat can be achieved by heat of burning paper or petrol

So kerosene requires lesser amount of heat than Wood to burn

In other words, the Ignition temperature of kerosene is much lower than wood

Substance like Kerosene that burn very easily are called Inflammable substances

These substances have very low Ignition temperature

Petrol, Diesel, CNG, LPG all are Inflammable substances

So we have to store them very cautiously so that they don’t come close to fire by accident

Revision

Ignition temperature is minimum temperature required for a substance to catch fire

Different substance has different Ignition temperature

Substances with low Ignition temperature are known as Inflammable substances

Kerosene, LPG, Petrol, Diesel all are inflammable substances

That’s all for now!