Redox

Understanding Redox

• Redox is a type of chemical reaction where oxidation and reduction occur simultaneously. This is a crucial concept to understand for the Chemical Reactions unit.
• Oxidation is the process of losing electrons.
• Reduction is the process of gaining electrons.
• An easy way to remember this is by using the acronym OIL RIG: Oxidation Is Loss, Reduction Is Gain.

Oxidation Numbers

• Oxidation numbers or oxidation states are assigned to atoms in a molecule to help identify the atom that has been oxidised or reduced in a redox reaction.
• The oxidation number of an atom in its elemental state is always zero.
• For monatomic ions, the oxidation number equals the charge of the ion.
• Oxygen usually has an oxidation number of -2, except in peroxides where it is -1.
• Hydrogen usually has an oxidation number of +1, except when it is bonded to metals where it has an oxidation number of -1.
• The sum of the oxidation numbers for all the atoms in a compound equals the overall charge of the compound.

Balancing Redox Reactions

• Balancing redox reactions involves ensuring equal changes of oxidation numbers on both sides of the reaction.
• This is commonly achieved using the half-reactions method where you separate the equation into two halves: one for oxidation and one for reduction.
• For each half-equation, balance the atoms and then the charges by adding electrons to one side.

Redox in Everyday Life and Industrial Processes

• Redox reactions have many applications, from generating electricity in batteries to bleach production and water treatment.
• Respiration, a vital process for life, is a redox process. Glucose is oxidised to produce carbon dioxide and water, releasing energy.
• Rusting is a redox reaction where iron is oxidised to form iron (III) oxide, and oxygen is reduced.
• Photosynthesis, the process plants use to convert sunlight into chemical energy, includes several redox reactions.