In chemistry, acid value (or "neutralization number" or "acid number" or "acidity") is the mass of potassium hydroxide (KOH) in milligrams that is required to neutralize one gram of chemical substance. Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties Potassium hydroxide is the Inorganic compound with the formula K[[hydroxide OH]] A chemical substance is a Material with a definite chemical composition. The acid number is a measure of the amount of carboxylic acid groups in a chemical compound, such as a fatty acid, or in a mixture of compounds. Carboxylic acids are Organic acids characterized by the presence of a Carboxyl group, which has the formula -C(=OOH usually written -COOH or -CO2H In Chemistry, especially Biochemistry, a fatty acid is a Carboxylic acid often with a long unbranched Aliphatic tail ( chain) which In a typical procedure, a known amount of sample dissolved in organic solvent is titrated with a solution of potassium hydroxide with known concentration and with phenolphthalein as a color indicator. Titration is a common laboratory method of Quantitative chemical analysis that is used to determine the unknown Concentration of a known Reactant In Chemistry, concentration is the measure of how much of a given substance there is mixed with another substance Phenolphthalein is a Chemical compound with the formula C 20 H 14 O 4 (often written as " HIn
The acid number is used to quantify the amount of acid present, for example in a sample of biodiesel. Biodiesel refers to a non-petroleum-based Diesel fuel consisting of short chain Alkyl ( Methyl or ethyl) Esters made by It is the quantity of base, expressed in milligrams of potassium hydroxide, that is required to neutralize the acidic constituents in 1 g of sample.

Veq is the amount of titrant (ml) consumed by the crude oil sample and 1ml spiking solution at the equivalent point, beq is the amount of titrant (ml) consumed by 1 ml spiking solution at the equivalent point, and 56. Titration is a common laboratory method of Quantitative chemical analysis that is used to determine the unknown Concentration of a known Reactant 1 is the molecular weight of KOH.
The molarity concentration of titrant (N) is calculated as such:

In which WKHP is the amount (g) of KHP in 50 ml of KHP standard solution, Veq is the amount of titrant (ml) consumed by 50 ml KHP standard solution at the equivalent point, and 204. 23 is the molecular weight of KHP. Potassium hydrogen phthalate, often called simply KHP, is a white or colorless ionic Solid that is the monopotassium salt of Phthalic acid
There are standard methods for determining the acid number, such as ASTM D 974 and DIN 51558 (for mineral oils, biodiesel), or specifically for Biodiesel using the European Standard EN 14104 and ASTM D664 are both widely utilised worldwide. ASTM International ( ASTM) originally known as the American Society for Testing and Materials is an international Standards organization that develops and publishes Deutsches Institut für Normung eV ( DIN; in English, the German Institute for Standardization) is the German national organization for Acid number (mg KOH/g oil) for biodiesel should to be lower than 0. Potassium hydroxide is the Inorganic compound with the formula K[[hydroxide OH]] Biodiesel refers to a non-petroleum-based Diesel fuel consisting of short chain Alkyl ( Methyl or ethyl) Esters made by 50 mgKOH/g in both EN 14214 and ASTM D6751 standard fuels. This is since the FFA produced may corrode automotive parts and these limits protect vehicle engines and fuel tanks.
As oil-fats rancidify, triglycerides are converted into fatty acids and glycerol, causing an increase in acid number. Rancidification is the decomposition of Fats Oils and other Lipids by Hydrolysis or Oxidation, or both (more properly known as, TAG or triacylglyceride) is Glyceride in which the Glycerol is Esterified with three Fatty acids It is the In Chemistry, especially Biochemistry, a fatty acid is a Carboxylic acid often with a long unbranched Aliphatic tail ( chain) which A similar observation is observed with Biodiesel aging through analogus oxidation processes and when subjected to prolonged high temperatures (ester thermolysis) or through exposure to acids or bases (acid/base ester hydrolysis).