Combustion Formula


Combustion Formula

What is combustion?

Combustion is a rapid chemical reaction of a substance with oxygen involving the production of heat and light. Combustion is an exothermic reaction accompanied by the development of heat so that temperature rises considerably.

Combustion reaction with insufficient oxygen produces carbon monoxide instead of carbon dioxide. In general combustion processes, oxidation-reduction reactions where oxidizing agent is the oxidant and the reducing agent is the fuel.

Combustion Formula is expressed by

Heat of combustion = Heat of formation of products – Heat of formation of reactants.

The easiest way to identify a combustion reaction is that the products always contain carbon dioxide and water.

  • Complete Combustion is an oxidation of hydrocarbon producing only carbon dioxide and water. Example for clean combustion is burning of candle wax, where the heat from the wick vaporizes wax (a hydrocarbon), which reacts with oxygen to release carbon dioxide and water
  • Incomplete Combustion is hydrocarbon oxidation that produces carbon monoxide and/or carbon (soot) in addition to carbon dioxide. Example of incomplete combustion is burning of coal, where a lot of soot and carbon monoxide is released.

Example 1

Combustion of methane

CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g)

Example 2

Burning of naphthalene

C10H8 + 12 O2 → 10 CO2 + 4 H2O

Example 3

Combustion of ethane

2 C2H6 + 7 O2 → 4 CO2 + 6 H2O

Example 4

Combustion of butane ( found in lighters)

2C4H10(g) +13O2(g) → 8CO2(g) +10H2O(g)

Example 5

Combustion of methanol ( wood alcohol)

2CH3OH(g) + 3O2(g) → 2CO2(g) + 4H2O(g)


Practise This Question

Both Arjun and Rahul went for jogging the next day and stopped at a place where kids were playing on a slide as shown below:

Two slides which are directed in the two opposite directions are combined by a vertical stairs in the midway between the two sliders. The lengths of both the slides are same.

Two kids Mia and Anu reached down after sliding down. How much distance has Mia to walk from A to reach Anu who is at B if AC = 5 m and width of the stairs = 1 m?