In standard electrode convention, is the reduction or oxidation half-reaction typically written first?

In standard electrode convention, the reduction half-reaction is typically written first because it represents the gain of electrons, which is fundamental to the concept of electrochemical cells. In electrochemistry, reduction is when an atom or ion gains electrons, leading to a decrease in oxidation state. The standard convention favors presenting reduction first as it allows for a more straightforward understanding of how electrochemical cells function, particularly in galvanic (voltaic) cells, where the flow of electrons is indicative of spontaneous reaction processes.

Reduction is seen as the primary reaction in the context of electrochemical cells because it is associated with the cathode, which is the part of the cell where reduction occurs and is responsible for electrical energy production. Conversely, oxidation, occurring at the anode, is secondary in this context and is depicted as a subsequent event in the overall electrochemical process. This organization clarifies the stoichiometry and provides a consistent and logical framework for analyzing redox reactions across different systems.

Moreover, when using standard electrode potentials, the values provided are listed for the reduction reactions when assessing cell potentials, reinforcing the focus on reduction as the standard representation in electrochemical conventions.