A chemical reaction occurs when the molecular structure of a reactant changes. This usually involves the removal or addition of atoms or molecules. The resulting product is chemically different from the original reactant. There are several types of chemical reactions, but most reactions fall into the following categories.
Synthesis Reaction
A synthesis reaction involves the formation of a product from two distinct molecules. The chemical equation for a synthesis reaction is A + B -> AB.
Single Displacement Reaction
A single displacement reaction involves the removal of one atom from one reactant and the subsequent joining of that atom to the second reactant. The chemical equation for a single displacement reaction is A + BC -> AC + B.
Double Displacement Reaction
A double displacement reaction involves the switching of atoms between two reactants. The chemical equation for a double displacement reaction is AB + CD -> AD + BC.
Decomposition Reaction
A decomposition reaction is a different type of chemical reaction. It involves the breakdown of a molecule into its individual parts. The chemical equation for a decomposition reaction is AB -> A + B
Combustion Reaction
A combustion reaction involves oxygen and a carbon compound. The resulting products are water, carbon dioxide, and heat. The equation for a complete combustion of a hydrocarbon is CxHy + (X + Y/2)O2 -> (X)CO2 + (Y/2)H2O. An example is the combustion of methane: CH4 + 2O2 -> CO2 + 2H2O.
Acid Base Reaction
In an acid-base reaction, a double displacement occurs. The hydrogen atom from one molecule is displaced and combines with the hydroxide ion of another molecule. The result is a salt compound and water. The chemical equation is HA + BOH -> BA + H2O. An example is the reaction of hydrochloric acid and sodium hydroxide: HCl + NaOH -> NaCl + H2O
Hydrolysis Reaction
A hydrolysis reaction takes place in water. The chemical equation for hydrolysis is A + H2O -> HA + OH-
Reference:
SAT Chemistry: Types of Chemical Reactions – Spark Notes