Nutrient medium. A medium or nutrient base (enrichment) is the main medium, the composition of which differs significantly from the composition of the model solution. The medium introduced into the system is equivalent to the reagent molecule participating in the reaction (compensates for its effect). If the medium is equivalent to the catalyst acid, then the catalyst is its presence in the system. In this case, the medium contains a certain number of [H + ] molecules, since it is equal to the number of metal ions before the reaction, and constitutes the alkaline nature of the medium. If the reaction system contains a medium that is equivalent to the catalyst base, then the electrostatic charge of the product (anions) was compensated for by it before the reaction. In these cases, the environment will also be alkaline. Pre-reaction medium The pre-reaction medium can be a certain concentration of electrons from the reaction center in the electron transport chain, which is equivalent to the addition of a reagent.