combustion an flames

• Combustion is a chemical process where a substance reacts with oxygen to give off heat and light
• An example of combustion is the burning of wood
• Combustible substances easily catch fire, such as paper, coal, and wood
• Non-combustible substances do not catch fire readily, like sand, water, and glass
• Fuel is the usable energy produced upon combustion of a substance, such as fossil fuels, biogas, and nuclear energy
• Ignition temperature is the lowest temperature at which a combustible substance catches fire when heated in air
• Inflammable substances have low ignition temperatures and can easily catch fire with a flame, like diesel, LPG, and acetone
• Fire is the result of a chemical combustion reaction between oxygen and fuel
• For fire to occur, three things need to be present: fuel, a heat source, and enough oxygen
• Flame is the visible and gaseous part of the fire, releasing light energy due to fuel combustion
• Smoke consists of solid unburnt particles dispersed in a gas, with the black color due to unburnt carbon particles
• Rapid combustion releases heat and light quickly, like the combustion of L.P.G
• Spontaneous combustion is when substances catch fire on their own without the application of heat, for example, forest fires
• Fire can be controlled by removing fuel, oxygen, or lowering the temperature below the ignition point
• Calorific value is the heat energy produced on complete combustion of 1 kg of fuel, expressed in kilojoules per kg
• Efficiency of a fuel is the proportion of energy released that is converted into useful work
• Burning fuels like wood, coal, and petroleum releases unburnt carbon particles, carbon monoxide, and carbon dioxide, causing respiratory problems and global warming
• Carbon monoxide is a poisonous gas produced by incomplete combustion of fuels
• Global warming is the rise in the earth's average temperature due to the release of carbon dioxide on combustion of fuels
• Acid rain is caused by emissions of sulphur dioxide and nitrogen oxide reacting with water molecules in the atmosphere, harmful to plants, land, and aquatic animals
• CNG (Compressed Natural Gas) is replacing diesel and petrol in automobiles due to being less polluting and cleaner