Reagensöverskott

Reagensöverskott is a Swedish term that translates to "reagent excess" in English. It refers to a situation in chemical reactions where one of the reactants is present in a larger amount than is stoichiometrically required to react completely with the other reactants. This is often done intentionally to ensure that a more expensive or limiting reactant is fully consumed, or to drive a reaction to completion.

In practice, the reactant present in excess is called the excess reagent, while the other reactant that is completely consumed is called the limiting reagent. The limiting reagent dictates the maximum amount of product that can be formed in a reaction. The amount of product formed is therefore determined by the initial amount of the limiting reagent, not the excess reagent.

Using a reagent in excess can have several benefits. It can increase the yield of the desired product by ensuring that the limiting reagent does not remain unreacted. It can also help to speed up the reaction rate, as a higher concentration of one reactant can lead to more frequent collisions with the other reactant. However, using a large excess of a reagent can also lead to waste of material and may complicate the purification process if the excess reagent needs to be removed from the product.

The concept of reagent excess is fundamental in stoichiometry and is considered when calculating theoretical yields and planning chemical experiments. It is a common practice in both laboratory settings and industrial chemical processes.