acid number

noun

Chemistry.

1. a number expressing the acidity of a substance, equal to the number of milligrams of potassium hydroxide needed to neutralize the free fatty acids present in one gram of the substance.

Example Sentences

For scientific purposes the result is often expressed as "acid number," meaning the number of milligrams of KOH required to neutralize the free acids in one gram of fat, but the commercial practice has been, and is, to express the fatty acids as oleic acid or in the case of palm oil, as palmitic acid, in some instances.

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For a more exact expression of the free acid in a given fat, the committee recommends that the ratio of acid number to saponification number be used.

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From his examination of this oil he reported these constants: d24–5, 0.942; refraction at 25°, 81.5; solidifying point, 6° to 5°; melting point, 8° to 9°; saponification number, 177.5; esterification number, 166.7; acid number, 6.2; acetyl number, 0; iodin number, 84.5 to 86.3.

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