Combustion and flame

Combustion & Flame

Acknowledgement

Information and pictorial illustrations to create this work have been drawn from class notes, prescribed text books and various internet resources. The author gratefully acknowledges the same. Any objections to the use of internet resources may please be indicated to suddurocks@yahoo.in so that the same can be removed from the illustrations used in this file.

This presentation is created with the sole intention of benefitting a large number of student community. This may not be used for any commercial purpose.

C o n t e n t s :

Combustion

Ignition Temperature

Inflammable Substances

Controlling Fire

Types of Combustion

Explosion

Fuel Efficiency

Burning of Fuels Leads to Harmful Products

C o m b u s t i o n

A chemical process in which a substance

reacts with oxygen to give off heat is called

Combustion.

The substance that undergoes combustion is

said to be combustible. It is also called a

Fuel.

The fuel may be solid, liquid or gas.

Sometimes, light is also given off during

combustion, either as a flame or as a glow.

Ignition Temperature

When the cloths of a person catch fire, the

person is covered with a blanket to

extinguish fire.

The lowest temperature at which a

substance catches fire is called its

Ignition Temperature.

Inflammable Substances

The substances which have a very low Ignition

temperature and can easily catch fire with a

flame are called Inflammable Substances.

Example : Petrol, alcohol, Liquified Petroleum

Gas (LPG),…Etc.

Controlling Fire

• When a fire bridge arrives, it pours water on the

fire. Water cools the combustible material so

that its temperature is brought below its Ignition

Temperature.

• This prevents the fire from spreading. Water

vapours also surround the combustible material,

helping in cutting off the supply of air.

• So, the fire is extinguished.

• We must never use water to put out an oil fire

because oil floats on water and the fire would

spread more.

• We must never use water to put out an Electric

fire because the person spraying water can

receive an electric shock.

Types of Combustion

When we bring a burning match stick or a gas lighter near the gas stove in the kitchen and turn on the knob, the gas burns rapidly and produces heat and light.

Such combustion is known as Rapid Combustion.

The type of combustion in which a material suddenly bursts into flames, without the application of any apparent cause is called Spontaneous Combustion.

E x p l o s i o n

When a cracker is ignited, a sudden reaction

takes place with the evolution of heat, light and

sound.

A large amount of gas found in the reaction is

liberated.

Such a reaction is called an Explosion.

Explosion can also take place if pressure is

applied on the cracker.

Fuel Efficiency

►The amount of heat energy produced on a complete combustion of 1kg of a fuel is called its Calorific Value.

►The value of a fuel is expressed in a unit called Kilojoules per Kg.

Burning of Fuels Leads to

Harmful Products

Carbon fuels like wood, coal, petroleum release unburnt carbon particles. These fine particles are dangerous pollutants causing respiratory diseases like Asthma.

Incomplete combustion of these fuels gives carbon monoxide gas. It is a very poisonous gas. It is dangerous to burn coal in a closed room. This gas produced can kill persons sleeping in that room.

Combustion of most fuels releases carbon

dioxide in the environment. Increased

concentration of carbon dioxide in the air

is believed to cause Global Warming.

Global warming is the raise in temperature

of the atmosphere for the earth. This

results, among other things, in the melting

of polar glaciers, which leads to a raise in

the sea level causing floods in the costal

areas. Low lying costal areas may even be

permanently submerged in water.

Some Interesting Pictures

Some Interesting Pictures

Some Interesting Pictures

Some Interesting Pictures

Some Interesting Pictures

Some Interesting Pictures

Some Interesting Pictures

Thank You !!!

Compiled By :

Sudarshan . S . K .

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