Yield in chemistry, also known as chemical yield and reaction yield, is the amount of product obtained in a chemical reaction. The absolute yield can be given as the weight in gram or in mol (molar yield). The yield is usually also given as a relative yield, which is the actual yield divided by the theoretical yield (the maximally reachable yield). The relative yield is usually given as a percentage value, the percent yield: Chemistry (in Greek: χημεία) is the science of matter and its interactions with energy and itself (see physics, biology). ... A chemical reaction is a process involving one, two or more substances (called reactants), characterized by a chemical change and yielding one or more product(s) which are different from the reactants. ... Weight is the force exerted upon an object by virtue of its position in a gravitational field. ... The gram or gramme, symbol g, is a unit of mass, and is defined in the SI system of units as one one-thousandth of a kilogram (i. ... The mole (symbol: mol) is one of the seven SI base units and is commonly used in chemistry. ... A percentage is a way of expressing a proportion, a ratio or a fraction as a whole number, by using 100 as the denominator. ...

The theoretical yield value always relates to one of the reactants. This is usually the limiting one, taking into account the molar relation of the reactants and the stoichiometry of the reaction. In chemistry, the reactants are the substances that exist at the start of a chemical reaction. ... In chemistry, stoichiometry is the study of the combination of elements in chemical reactions. ...

The maximal yield of a chemical reaction would be 100%, a value that is never reached. Yields above about 90% are called very good, yields above about 75% are called good, yields below about 60% are called modest, yields below about 30% are called poor.

Example

This is an example of an esterification reaction where one molecule acetic acid reacts with one molecule ethanol, yielding one molecule ethyl acetate (a bimolecular second-order reaction of the type A + B → C): Esterification is the general name for a chemical reaction in that an ester is the reaction product. ... The chemical compound acetic acid (from the Latin word acetum, meaning vinegar), systematically called ethanoic acid, is the acid that gives vinegar its sour taste and very pungent smell when at high concentrations. ... Ethyl alcohol, also known as ethanol or grain alcohol, is a flammable, colorless chemical compound, one of the alcohols that is most often found in alcoholic beverages. ... Ethyl acetate, also known as acetic acid ethyl ester, ethyl ethanoate, or acetic ester, is a clear, flammable liquid with a characteristic, not unpleasant smell like certain glues or nail polish removers. ... Order in the context of a chemical reaction is a concept of reaction kinetics, a subdiscipline of physical chemistry. ...

120 g acetic acid (60 g/mol, 2.0 mol) was reacted with 230 g ethanol (46 g/mol, 5.0 mol), yielding 132 g ethyl acetate (88 g/mol, 1.5 mol). The yield was 75%.

1. The molar amount of the reactands is calculated from their weight (acetic acid: 120 g ÷ 60 g/mol = 2.0 mol; ethanol: 230 g ÷ 46 g/mol = 5.0 mol).
2. Ethanol is used in a 2.5-fold excess (5.0 mol ÷ 2.0 mol).
3. The theoretical molar yield is 2.0 mol (the molar amount of the limiting compound, acetic acid).
4. The molar yield of the product is calculated from its weight (132 g ÷ 88 g/mol = 1.5 mol).
5. The yield is calculated from the actual molar yield and the theoretical molar yield (1.5 mol ÷ 2.0 mol × 100% = 75%).