Combustion and Flame Flashcards
What does magnesium form when burnt? what is its formulae?
Magnesium oxide
=> Magnesium + Oxygen → Magnesium Oxide + Heat and Light
2Mg + O2 → 2MgO + ∆
Describe the combustion in our body.
Food is broken down by reaction with oxygen and heat is produced.
Why don’t we call the burning of sun as combustion?
In the sun, heat and light are produced by nuclear reactions so you don’t call it as combustion.
How do forest fire develop?
During extreme heat of Summer, at some places dry grass catches fire from the grass its spreads to trees and very soon before forests gets on fire.
What is combustion?
Combustion is a chemical process in which a substance reacts with oxygen to give of heat. Combustion requires three main constituents which are:
Fuel
Air( oxygen )
Low Ignition temperature
What is a fuel?
Fuel is the substance that undergoes combustion. It is also called combustible substance. The fuel may be solid, liquid or gas.
What is ignition temperature?
The lowest temperature at which a substance catches fire is called it ignition temperature.
How are Matchsticks made? How does it work? what is their history?
Nowadays matchsticks are made with antimony trisulphide, potassium chlorate, powdered glass and a little red phosphorus. When the match is struck against the Rough surface some red phosphorus gets converted into white Phosphorus, this immediately reacts with potassium chlorate in the matchstick head to produce in a heat to ignite and antimony trisulphide and starts the combustion. More than 5000 years ago small pieces of pinewood were dipped in Sulphur and used as matchsticks in Egypt later on, a mixture of antimony trisulphide, potassium chlorate and white phosphorus with some glue and starch was used as a Matchstick but due to white phosphorus danger it was continued and shifted to today’s matches.
Why does the paper doesn’t catch fire if it is made as a cone and filled with water?
The heat supplied to the paper cup is transferred to the water by conduction so in the presence of water the ignition temperature of paper is not reached hence it does not burn. If we continue eating the cup we can even boil the water.
What are inflammable substances?
The substances which have very low ignition temperature and can easily catch fire with a flame are called in flammable substances. for example petrol, alcohol, liquefied petroleum gas ( LPG ), etc
How does water put out fire?
Water cools the fuel material so that its temperature is brought below its ignition temperature preventing the fire from spreading. Water vapours also surround the combustible material cutting of the supply of air. So, the fire is extinguished.
What is the telephone number of the fire service in your area?
101
Why does CO2 extinguish fire and is the best extinguisher?
CO2 being heavier than oxygen covers the fire like a blanket, since the contact between the fuel and the oxygen is cut off, the fire is controlled. The added advantage of Co2 is that, in most cases it does not harm the electrical equipment. It can be stored at high pressure as liquid in cylinders when released from the cylinder CO2 expands enormously in volume and cool down the fuel. So, it not only forms of blanket around the temperature but also cools down the temperature of the fuel below its ignition temperature.
Another way to get CO2 is to release a lot of dry powder of chemicals like sodium bicarbonate (baking soda) potassium bicarbonate near the fire as these chemicals give off CO2.
Why don’t some fuels give out flames in combustion?
The substances which we vaporise during burning give out flames and those who don’t they do not.
A circular blackish ring is formed on a glass plate/slide put upon a candle flame. what does it indicate?
It indicates the deposition of unburnt carbon particles present in the luminous zone of the flame.
