Halvreaksjonsteknikk

Halvreaksjonsteknikk, commonly known in English as the half‑reaction method, is a systematic approach used in electrochemistry to analyse and balance redox equations. The technique involves separating a redox reaction into its constituent oxidation and reduction half‑reactions. Each half‑reaction is written and balanced independently for mass and charge, often employing the ion‑electron method. For species in aqueous solutions, the oxidation half‑reaction is balanced by adding appropriate amounts of electrons, while the reduction half‑reaction is balanced by adding electrons and, when necessary, hydrogen ions or hydroxide ions to satisfy charge and atom balances. In non‑aqueous media the balance may require the use of a solvent or complexing agent.

After both half‑reactions have been independently balanced, the number of electrons on each side is made equal by multiplying the entire half‑reaction with the smallest common multiple. The two equations are then added together, cancelling the electrons and any spectator ions that are present in both sides. The resulting equation represents the overall balanced redox process and is useful for determining stoichiometric relationships, calculating cell potentials, and predicting product formation.

This method is highly valuable in teaching because it provides a clear visualisation of electron flow and the role of species as oxidizing or reducing agents. It is also instrumental in the design and analysis of electrolytic cells, galvanic cells, and in the interpretation of spectroelectrochemical data. In industrial chemistry, halvreaksjonsteknikk assists in the optimisation of processes such as metal extraction, corrosion prevention, and battery development, where precise control of redox behaviour is critical.