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Methods & Processes
Comparatively Speaking--Analytical Methods: The mg KOH/gm System
By: Anthony O'Lenick, Jr., Siltech LLC
Posted: December 22, 2009
page 2 of 2
The relationship between the mg KOH/gm value and molecular weight is an important formula. The apparent molecular weight (AMW) of any material can be determined by the following formula:
AMW = 56,110/mg KOH/gm
Since the number of mg KOH per gram can be determined by titration, this value is independent of the type or concentration of the pure compound. If one had two different concentrations of a fatty acid in isopropanol and water and wanted to make a salt, an acid value titration could be run on both samples.
From the observed acid value, a required amount of base can be determined to exactly neutralize the acidity present. The alkali value of the base used could be used to determine the exact quantity of each type of base used. The values provided by this system are colligative; that is, not related to the specific species or combination of species that contribute the acidity.
