Combustion Reactions of Hydrocarbons and other Fuels

Understanding Combustion

Combustion is a chemical reaction that occurs between a fuel and an oxidant, resulting in heat and light. In the context of hydrocarbons, the oxidant is typically oxygen.

Complete combustion of a hydrocarbon fuel produces carbon dioxide (CO2) and water (H2O). It requires plenty of air (more specifically, oxygen).
- For example, the combustion reaction of methane (CH4), the simplest hydrocarbon, is:
  
  CH4 + 2O2 –> CO2 + 2H2O
Incomplete combustion occurs when the oxygen supply is limited. The products of this reaction can include carbon (C), carbon monoxide (CO), and water (H2O) along with carbon dioxide.
- For example, if methane had limited oxygen supply, it might produce the following reactions:
  
  CH4 + O2 –> C + 2H2O
  
  CH4 + 1.5O2 –> CO + 2H2O

Other fuels, such as alcohols, undergo similar combustion reactions.
- For example, the combustion of ethanol (C2H5OH), an alcohol, would produce carbon dioxide, water and release energy:
  
  C2H5OH + 3O2 –> 2CO2 + 3H2O

The products of combustion reactions, particularly carbon dioxide and carbon monoxide, are notable greenhouse gases contributing to global warming and climate change.
Carbon monoxide is also a toxic gas, harmful to humans and animals when inhaled.
Incomplete combustion producing carbon results in the formation of soot, which can cause respiratory problems in humans and is a major contributor to air pollution.

Combustion reactions are exothermic, meaning they release energy, often in the form of heat and light.
The energy released in a combustion reaction is used for numerous things such as heating homes, powering engines, and generating electricity.