Combustion with Hydrocarbons

Combustion Reaction

Related Notes

• This is related to Combustion Reactions.

• Combustion is a reaction in which a substance reacts with oxygen. This releases light and heat energy (exothermic). This is commonly called burning.

What does "exothermic" mean?

• Let’s break it down.
• Exo means “external” or “outside”.
• Thermic means “relating to heat”.
• Therefore, exothermic would be external heat or heat being emitted to its external surroundings.

Hydrocarbons as Fuels

• Firstly, a fuel is a substance that will undergo a chemical reaction to produce a large amount of useful energy.
  • Fuel is used to produce electricity and heat, and run everyday objects like engines.
  • Many fuels consist of hydrocarbons.
• Hydrocarbons are molecules that only consist of hydrogen and carbon atoms.
  • Hydrocarbons are good sources of fuel because they combust/burn very well, due to the heat produced relative to their molecular size.
  • Hydrocarbons can also ignite faster dependent on their molecular size. Smaller hydrocarbons will ignite faster than larger hydrocarbons.

Types of Combustion

• There are many types of combustion.
  • This is due to the fact that the environment can affect how well a substance undergoes combustion.

Complete Combustion

• Complete combustion is when combustion is conducted with an excess amount of oxygen.
• This reaction produces carbon dioxide and water.

Complete Combustion Formula

• Let’s break all of these parts of the equation down.
  • is the hydrocarbon.
  • is oxygen.
  • is carbon dioxide.
  • is water.
• We can see here that hydrogen and carbon have oxidised and chemically bonded with the oxygen, therefore producing carbon dioxide and water.

Balancing Tip

• In order to effectively balance this equation, you can start by balancing carbon, then hydrogen, then oxygen.

Incomplete Combustion

• Incomplete combustion is when combustion is conducted with a limited amount of oxygen.
• The reactants stay the same as a Complete Combustion and the reaction still produces heat and water. However, the products are slightly different.

Incomplete Combustion Formula

• Let’s break this down.
  • is the hydrocarbon.
  • is oxygen.
  • is carbon (soot) and is carbon monoxide.
  • is water.
• Incomplete combustions can produce both soot and carbon monoxide, only soot, or only carbon monoxide. (You can also get carbon dioxide!)
• The products formed are dependent on the amount of oxygen present.