A reaction in which oxidation and reduction occur at the same time is a redox reaction.
Oxidation:
Loss of electrons
Gain of oxygen
Loss of hydrogen
Reduction:
Gain of electrons
Loss of oxygen
Gain of hydrogen
Note: Roman numerals next to an element’s name are the oxidation state of the ion, eg. Iron (II) and Iron (III). The reaction product formula depends on this.
Reducing agents are oxidized and oxidizing agents are reduced
Oxidation state: Oxidation state highlights electron movement in an reaction
Indicators of a redox reaction
Potassium manganate (VII) is an oxidising agent; when added to a reducing agent changes from purple to colourless
Potassium iodide is a reducing ; when added to an oxidising agent changes colorless to red - brown