occur when a compound, usually one containing carbon, combines with the oxygen gas in the air. This process is commonly called . Heat is the most-useful product of most combustion reactions.
Combustion reactions always involve molecular oxygen O2. Anytime anything burns (in the usual sense), it is a combustion reaction. Combustion reactions are almost always exothermic (i.e., they give off heat). For example when wood burns, it must do so in the presence of O2 and a lot of heat is produced:
Classifying Synthesis, Decomposition, and Combustion Reactions
For example, simple hydrogen gas combined with simple oxygen gas can produce a more complex substance-----water!
The chemical equation for this synthesis reaction looks like:
reactant + reactant -------> product
To visualize a synthesis reaction look at the following cartoon:
In the cartoon, the skinny bird (reactant) and the worm (reactant) combine to make one product, a fat bird.
In a decomposition reaction a more complex substance breaks down into its more simple parts.