Commonly used in school laboratories for experiments, the Bunsen burner uses natural gas as its fuel. Natural gas is almost pure methane, which is a hydrocarbon (CH4).
The Bunsen burner has an air hole to allow complete or incomplete combustion. When the air hole is open, air enters the chimney and combines with the natural gas, resulting in complete combustion. This produces a very hot blue flame. When the air hole is closed, there is not enough oxygen to mix with the natural gas, resulting in incomplete combustion. This, in turn, produces a yellow flame, also called the safety flame, which is brighter than the blue flame but transfers less heat energy.