this chapter is about the combustion how we protect from combustion , layer of flame and acid rain

1. COMBUSTION
AND FLAME
MADE BY:- DEWANG KANOJIYA
CLASS:- VIII B
ROLL NO :- 8224

2. INTRODUCTION
• fuel :- Substances which provide energy on buying in air are called fuels. They
may be of various types :
• Solid fuel Such as wood, coal ,cowdug cakes , Charcoal (prepare from wood)
• Liquid fuel like kerosene, perol and diesel.
• Gaseous fuel such as CNG ,LPG and Coal gas.

3. WHAT IS COMBUSTION
• It is a chemicalprocess I which a
substance react with oxygen to given off
heat. Sometime light , either as a flame
or as golw is also given off during
combustion.
• In the sun , heat and light are produced
by nucleare reaction.

4. IGNITION TEMPERATURE
• The lowest temperature at which the
substance catches fire is known as
ignition temperatur. A substance cannot
catch fire or burn as long its
tempareture is lower then its ignition
temparature
•

5. CONTENTS OF MODERN MATCH STICK
• Wooden match stick, that has antimony trisulphte and poassium chorate at
its head.
• The rubbing surface , present on the match box, has powderd glass and a
little red phosphorus.
whenthe head of a match stickis rubbed against the rubbin surface –
red phosphorus ( of surface) –converts into white phosphorus
white phosphorus react with atimony trisulphide ( in head ) – start
combustion

6. INFAMABLE SUBSTANCES
• The substances that have tempareture an can easiy catch fire with are
flame areknown as inflamable substance.
• For example :- alcohol and petrol

7. SUPPORTER FOR COMBUSTION
• The gaseous environment that supports combustion of a
combaustible substance is called supporter of combustion
• Smaller the size of combustible particlies, faster is the rate of
combustion
• Nature of combustible substance:
inflammable substance burn faster as compared to substance
such as wood

8. FIRE EXTINGUISHER
• A substance which disrupts the contact between
and and the fire is called extinguisher.
1. Water is very good substance in fire fighting as it
cool down the fuel below its ignition
temperature.
2. Sand and soil may act as a good fire extinguisher
particularly for buring of oils.
3. If the clothes of aperson catch fire it may be put
off with the help of blanket
4. Water should not be used to extingush fire
involving electrial equipment or

9. 5. For fire involving electrical equipment
and inflammable material such as petrol
, carbon dioxide is best extinguisher.
Carbon dioxide being heavier than oxygen,
cover the fire like a blanket . As the contact
between the fuel and oxygen is cut off. The
fire is controlled. Compressed carbon
dioxide stored in cylinder when realeas on
fire causes:
• Formation of blanket around the fire
• Cool down the temperature of the fuel.
Carbon dioxide does not harm electrical
equipment

10. TYPE OF COMBUSTION
• Rapid Combustion: Combustion in which a gas burns
quickly producing heat and light in the process. E.g. LPG
• Spontaneous Combustion: Combustion in which a
material bursts into flames suddenly without applying
heat. E.g. Phosphorus which burns at room
temperature.Spontaneous combustion of coal dust often
causes accidental fires in coal mines. Heat from the sun
or lighting may also cause spontaneous forest fires.
• Explosion: When a material bursts suddenly to produce
heat, light and sound on the application of heat or
pressure, it is called an explosion. E.g. Crackers and
fireworks which release a large amount of gas too.

11. STRUCTURE OF FLAME
• The substance which from vapour during heating,
burn with a flame. A flame is a region where
combustion of gaseos substance or vapour takes
place.
• The flame has three distinct zones:-
• Black zone :- it is the innermost zone of unburnt
vapours.
• Brigjt and luminous (yellow)zone:- it is the middle
zone. Brightness of this zone is due to the glow of
unburnt carbon paticles.
• Blue zone :- it is the outer zoneof complete
combustion. It ia the hottest and non-luminous
zone.

12. CALORIFIC VALUE
• The amount of heat energy produced on
complete combustion of 1kg of a fule is
called calorific value.
• The calorific value of a fuel is expressed in a
unit known as kilojoule per kg (kj/kg).

13. WHAT IS ACID RAIN?
• rainfall made so acidic by
atmospheric pollution that it causes
environmental harm, chiefly to forests
and lakes. The main cause is the
industrial burning of coal and other
fossil fuels, the waste gases from
which contain sulphur and nitrogen
oxides which combine with
atmospheric water to form acids.

14. HOW TO CONSERVE FUEL
• Collect all material required while cooking at one place
before switching on the gas,
• Check the pressure of tyres regularly,
• Choose walking over using cars or motorbikes for short
distances, and
• Use public transportation for travelling instead of private
vehicles.

15. BURNING OF FUEL LEAD TO HARMFUL PRODUCT
• Carbon fuels such as wood, coal, petroleum release unburnt carbon particles in the
environment. These particles are very dangerous pollutants and cause respiratory
diseases for example asthma.
• When fuels are incompletely burnt, they release carbon monoxide gas into the
atmosphere. This gas is very dangerous as it is poisonous in nature. If we burn coal in
a closed room, then the person sleeping in that room will be killed by the action of
carbon monoxide.
• The combustion of fossil fuels also releases a large amount of carbon dioxide into the
atmosphere. Carbon dioxide is a greenhouse gas which is responsible for Global
warming is a rise in the overall temperature of earth’s surface. This leads to melting of
polar caps and rise in the sea level and further results in flooding of coastal regions.
• Burning of coal and diesel release sulphur dioxide gas. This gas is extremely corrosive
and suffocating in nature. Petrol gives off oxides of nitrogen. The oxides of sulfur and
nitrogen get dissolved in rainwater and form acids. This is known as acid rain. This
water is very harmful to plants, animals, and various monuments.

16. THANK YOU