Tag: chemical properties of carbon compounds

When most fuels burn, the products include carbon dioxide and water.
Fuels are hydrocarbons. Combustion of hydrocarbons releases carbon dioxide and water.
$\displaystyle  CH _4 + 2O _2 \rightarrow CO _2 + 2H _2O$

Petrol engine gives off gaseous oxides of nitrogen.
During combustion of fuel at high temperature, nitrogen and oxygen of air combine to form $NO$ and $\displaystyle NO _2$ and are released with the exhaust gas.

Burning of coal and diesel release, sulphur dioxide gas, which is extremely corrosive and suffocating in nature.

Use of petrol and diseal as fuel in automobiles are now replaced by CNG.
CNG is compressed natural gas (methane stored at high pressure).
Combustion of CNG results in fewer unwanted gases than petrol and diseal.
Also CNG is safer than petrol and diseal as CNG is lighter than air and disperses quickly when released.

A chemical process in which a substance reacts with oxygen to give off heat is combustion.
For example, when C is burnt in excess air, it gives carbon dioxide and heat.
$\displaystyle C + O _2 \rightarrow CO _2 + $ heat

Nitrogen oxides is emitted in car exhaust and is a cause of acid rain.
Fuels such as coal for engine and petroleum for vehicle having little quantity of sulphur and nitrogen. On combustion, such fuels form oxides of sulphur and nitrogen which is environmental hazard.

Complete combustion of alkene require sufficient oxygen.
Alkene on combustion in presence of sufficient oxygen will give carbon dioxide and water.
$\displaystyle CH _2=CH _2 + 3O _2 \rightarrow 2CO _2 + 2H _2O$

The reaction $\displaystyle 2C _3H _8 + 7O _2 \rightarrow 2CO _2 + 8H _2O + 2CO + 2C$  is an example of incomplete combustion reaction. Propane, on incomplete combustion in  presence of excess oxygen gives carbon dioxide, water, carbon monoxide and carbon.

Alkanes are used as fuel, because there is evolution of large amount of heat during combustion. Here, the purpose is to obtain as much heat as possible from given mass of fuel.

LPG burns more cleanly than higher molecular weight hydrocarbon because it releases less pollutants.  Being a gas, LPG does not cause ground or water pollution hazards, but it  causes air pollution.
Note: LPG is liquefied petroleum gas which is compound of butane and propane used in cooking fuel ( in heating appliances, cooking equipment) , motor fuel (in vehicles) and refrigeration.