Combustion and Flame Test - 8

Though hydrogen is a highly combustible gas, because of its high calorific value, it is used as rocket fuel, for cutting and welding metals in the form of oxyhydrogen flame and as a car fuel under stringent safety conditions.

Inflammable substances have very low ignition temperatures, so they catch fire easily.                 e.g., alcohol, ether, carbon disulphide, benzene, synthetic fibres etc.

Incomplete combustion of a fuel results in the formation of unburnt carbon and some poisonous gases like ′CO′ and oxides of nitrogen which cause air pollution leading to many respiratory problems.

Carbon dioxide is the best extinguisher for inflammable materials like petrol, because it is heavier than oxygen, it covers fire like a blanket. Since, the contact between the fuel and oxygen is cut off, the fire is controlled. Secondly, it does not harm the electrical equipment.                 It can also be used to put out fires involving electrical equipment.

The type of fuel involved in the combustion determines the type of flame (colour and temperature of a flame varies with   the chemical composition of the fuel).

Global warming may cause glaciers to melt, which may lead to a rise in the sea level and thus submerge low lying areas.

Butane is an odourless gas, so it is mixed with mercaptan such that if the gas leaks in air, it can be easily detected due to its peculiar choking smell and prevents it from explosion.

The availability of hydrogen is less and also forms an explosive mixture with air or oxygen and causes explosion if it leaks out. Its storage and transport are difficult.

Gaps are left in between logs of wood placed in chullahs to allow free movement of air, which helps in combustion.