Formation of Methane Oxy acetylene welding Acetylene burned in this torch produces a flamehot enough to melt iron
The hydrocarbons in which each carbon atom is bonded to four neighboring atoms by four single covalent bonds are known as saturated hydrocarbons. The term saturated means that each carbon has as many atoms bonded to it as possible. Eg: Methane, Ethane, etc.
A hydrocarbon containing a multiple bond, either double or triple is known as an unsaturated hydrocarbon. Because of the multiple bond, two of the carbons are bonded to fewer than four other atoms. These carbons are thus said to be unsaturated. Eg: Ethene, acetylene, etc.
Acetylene, C2H2 is an unsaturated hydrocarbon containing a triple bond. A confined flame of acetylene burning in oxygen (oxy acetylene) is hot enough to melt iron, which makes acetylene a choice fuel for the welding.
In a saturated hydrocarbon, all the carbon atoms are bonded to four other atoms whereas in an unsaturated hydrocarbon, some of the carbon atoms may only be bonded to three or two other atoms. The number of atoms bonded to each of the two middle carbons of n – butane is four, whereas each of the two middle carbons of 2 – butene is bonded to three other atoms i.e., a hydrogen and two carbons.