Oxidaton

Oxidation is a process in which Oxygen is added to a element or when hydrogen is removed from the molecule or electrons are removed from the atom.

Introduction:

For example:

2H₂(g)  + O_2(g)  ------> 2H₂O(g)
2Mg(s)  + O_2(g)  -----> 2MgO(s)

Here hydrogen is oxidized because oxygen is added to Hydrogen. Magnesium is also oxidized by oxygen.
2H₂S(g)   + O2(g)    ----> 2S(s)  + 2H2O(l)

In the above reaction H₂S is oxidized since Hydrogen is removed from H₂S
Zn (s)--------> Zn²⁺ (aq) + 2e-

In the above example the Zinc is oxidized into Zn²⁺. Zinc looses two electron to form the ion. Since it looses electron it is oxidation. Oxidation is a part of redox reaction. In this type of reaction reduction and oxidation takes place simultaneously.

Addition of other electronegative elements are also considered as oxidation.For example
Mg(s) +  F₂(g)  -----> MgF₂(s)
2K(s)  + Cl₂(g)  ----> 2KCl(s)

In the above example Magnesium is oxidized to Mg²⁺ by flourine and  potassium is oxidized to K⁺ by the chlorine. 

Examples of Oxidaton Reaction

Combustion of methane is an example of oxidation reaction.  For example methane is oxidized to carbon dioxide and water when ignited
CH₄  +2 O₂  ----->  CO₂  + 2H₂O
Iron article is oxidized to Fe₃O₄ when exposed to air and water. Oxidation is unwanted in the case of iron and to prevent it normally painting is done on the Iron.  Galvanization of Iron is another method to prevent the oxidation of Iron which is called as corrosion.   Chrome plating of Iron is another method in which Iron is coated with Chromium so that the iron is not oxidized.
Oxidation process finds many application.  Redox reaction which involves oxidation and reduction is used for volumetric determination of unknown amount of substance from the known amount of the compound.