Chemical Reactions

In a chemical reaction, one or more substances change into new substances. The change in composition of the compound results from a chemical reaction. In a chemical reaction, the starting substances are called reactants and the new substances are called the products.

Types of chemical reactions
When dealing with chemical reactions, the type of chemical reactions can be split into five different categories. The five different categories are:
- Combination reactions:
In this type of reaction two or more substance react to make one substance.
E.g. S + O2 = SO2

- Decomposition reactions:
In this type of reaction, ne substance reacts (breaks down) to form two or more simpler substances.
E.g. CaCO3 = CaO + CO2

- Single replacement reactions:
In this type of reaction, atoms of an element replace atoms of a second element in a compound.
E.g. Fe + CuSO4 = FeSO4 + Cu

- Double replacement reactions:
In this type of reaction there is an exchange of positive ions between two compounds.
E.g. 3H2SO4 + 2Al(OH)3 = 6H2O + Al2(SO4)3

- Combustion reactions:
This is when oxygen reacts with another substance, often producing energy in the form of light and heat.
E.g. CH4 + 2O2 = 2H2O + CO2