Redox Reactions What is the meaning of REDOX? R E D O X Ox idation Red uction
Examples of Redox Reactions which occur in daily life
Defn 1 (In terms of oxygen) Oxidation = addition/gain of oxygen A substance that gains oxygen is said to be oxidised. Reduction = removal/loss of oxygen. A substance that loses oxygen is said to be reduced.
Example based on Defn 1 (In terms of oxygen)
Zn + PbO -> ZnO + Pb
Zinc (Zn) is oxidised because it gains oxygen to form zinc oxide .
Lead (II) oxide (PbO) is reduced because it loses oxygen to form lead .
When one substance is oxidised, another substance must be reduced. Oxidation and reduction take place at the same time. Such reactions are called REDOX reactions.
Example based on Defn 1 (In terms of oxygen) 2. Fe 2 O 3 + 3CO -> 2Fe + 3CO 2 Carbon monoxide (CO) is oxidised. Iron (III) oxide (Fe 2 O 3 ) is reduced.
Defn 2 (In terms of hydrogen) Oxidation = removal/loss of hydrogen A substance that loses hydrogen is said to be oxidised. Reduction = addition/gain of hydrogen. A substance that gains hydrogen is said to be reduced.
H 2 S + Cl 2 -> 2HCl + S
The substance oxidised is
h ydrogen sulfide (H 2 S) because it loses hydrogen to form sulfur .
The substance reduced is
c hlorine (Cl 2 ) because it gains hydrogen to form hydrogen chloride .