Combustion and Flame
Combustion is a chemical process in which a substance reacts with oxygen to produce heat and light. On the basis of combustion, substances can be divided into combustible and non-combustible substances.
Fuel is a combustible substance that releases its energy either through a chemical reaction such as combustion or nuclear reaction. On the basis of physical state, fuels are categorised into solid, liquid and gaseous fuels. Examples of fuels include cow dung, wood, coal, charcoal, petroleum, compressed natural gas and liquefied petroleum gas.
Fuel efficiency is expressed in terms of its calorific value.
Harmful products of combustion of fuels include unburnt carbon particles, carbon monoxide, oxides of sulphur and nitrogen and carbon dioxide.
When rain water dissolves the oxides of sulphur and nitrogen, acid rain is formed.
The increased concentration of carbon dioxide in air causes global warming.
Combustion takes place only in the presence of air or oxygen.
Ignition temperature is the minimum temperature at which a substance catches fire and starts burning. Inflammable substances have very low ignition temperature and can easily catch fire with a flame.
Fire is the process of the oxidation of a combustible material by which heat and light are released and product such as carbon dioxide is formed. Fire can be controlled by removing one or more things that are essential for combustion.
Fire extinguisher stops the supply of air or brings down the temperature of fuel.
Water is the most common fire extinguisher.
Carbon dioxide is the best extinguisher for fires involving electrical equipments and inflammable materials.
Fire safety measures should to be taken to prevent fire hazards. Burn can be classified into first degree burns, second degree burns and third degree burns.
When a substance vapourises during burning, a shiny light producing heat is obtained. This shiny light is called flame. Different zones of the flame include outer or non-luminous zone, middle or luminous zone and innermost or dark zone. Yellow flame indicates incomplete combustion of a substance due to the insufficient supply of oxygen. Blue Flame shows complete combustion of a substance.
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