Reaktans

Reaktans is a term used to describe substances that participate in a chemical reaction and are consumed to form products. In English, the standard term is reactants, and reaktans is a cognate used in several languages to convey the same idea. Reaktans are the starting materials of a reaction and appear on the left side of a balanced chemical equation. Their quantities are expressed by coefficients that reflect the mole ratios required to produce the specified products.

Reaktans play a central role in stoichiometry and reaction kinetics. The amounts of reaktans determine the extent of the reaction, and when one reactant is exhausted, the reaction cannot proceed further (the limiting reactant). Some reaktans may be present in excess, while others are consumed completely. In many cases, the reaction conditions (temperature, pressure, solvent) influence the rate at which reaktans are transformed into products, but the identity of the reaktants themselves remains fixed by the chemical equation.

Not all substances involved in a reaction are reaktans. Catalysts, for example, participate in the reaction mechanism but are not consumed in the overall process, so they are typically not counted among the reaktans. Solvents can act as reaktans if they undergo chemical change during the reaction; otherwise they may simply serve as media. Distinguishing reaktans from products and from non-consumed participants is essential for balancing equations and for planning practical syntheses.

Examples include the combustion of hydrogen and oxygen to form water (H2 and O2 are reaktans), the neutralization of an acid by a base (acid and base are reaktans), and the esterification of alcohols with carboxylic acids.