Redox Reactions

Redox Reactions

Definition and Basics:

  • A Redox reaction is a chemical reaction that involves a transfer of electrons between two species.
  • This reaction comprises two half reactions— oxidation (where electrons are lost) and reduction (where electrons are gained).
  • The species gaining the electrons is the oxidising agent (or oxidant) and the species losing the electrons is the reducing agent (or reductant).
  • Redox reactions form the basis of electricity generation in batteries and fuel cells.

Balancing Redox Reactions:

  • Oxidation numbers help to balance chemical equations in redox reactions.
  • Oxidation number of an atom increases if it loses electrons and decreases if it gains electrons.
  • Half-equation method is an efficient process to balance redox equations by balancing oxidation and reduction half-equations separately, and then adding them together.

Identifying Redox Reactions:

  • Presence of a change in the oxidation states of some atoms in the reactants indicates a redox reaction.
  • A redox reaction always involves a change in the oxidation number of at least two elements.

Redox Reactions in Metallurgy:

  • Redox reactions play a central role in the extraction of metals. Ores are often compounds of the metal with oxygen, sulphur or a halogen.
  • The metal species are reduced to their elemental form by the loss of oxygen, gain of hydrogen or loss of a more electronegative element.
  • Important metallurgical processes like roasting and smelting are based on redox principles.

Redox Titrations:

  • In Redox titration, the reaction between the analyte and titrant forms the basis for quantitative chemical analysis.
  • Commonly used reagents for redox titration include potassium permanganate, potassium dichromate, and iodine – often used as oxidising agents.

Real-World Applications:

  • Redox reactions are employed in numerous practical applications including energy production, such as in batteries and fuel cells, and various industrial processes like metal extraction.
  • Corrosion can be understood as a redox process. For example, rusting of iron is a redox reaction with oxygen (from air) and water.