Reaktionsüberschüsse

Reaktionsüberschüsse are a concept in analytical chemistry and chemical kinetics that describe the excess amount of one reactant relative to the stoichiometry of a chemical reaction. When reactants are mixed, they are rarely present in the exact molar ratios required for complete consumption of all species. The reactant that is completely consumed is called the limiting reactant, while the other reactants are present in excess. The difference between the initial amount of an excess reactant and the amount that reacts according to the stoichiometry is the reaction surplus.

Understanding reaction surpluses is crucial for several reasons. In industrial processes, it can be more economical to use an excess of a cheaper reactant to ensure complete conversion of a more expensive one. This also helps to drive the reaction to completion. In laboratory settings, controlling reaction surpluses can influence reaction rates and product yields. For instance, a large excess of a solvent can act as a heat sink, moderating exothermic reactions.

The calculation of reaction surpluses begins with determining the limiting reactant by comparing the initial molar amounts of reactants to their stoichiometric coefficients. Once the limiting reactant is identified, the theoretical amount of each excess reactant that will be consumed is calculated. The surplus is then found by subtracting this theoretical consumed amount from the initial amount of the excess reactant. This concept is fundamental to stoichiometry and is applied in various fields, including chemical engineering, pharmaceuticals, and environmental science.