Questions about making soap
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I would like to ask: based on the equation RCOOH + NaOH = RCOONa + H2O, how can I calculate the molecular weight of this mixed fatty acid? If I can determine the molecular weight of the fatty acid, can I then calculate the molecular weight of its sodium salt?
That is a mixture; the proportions vary depending on the different oils used
For accuracy, it is first necessary to determine the composition of the mixed fatty acids using GC-MS, after which it can be calculated based on the stoichiometric formula.
Consider whether what you are trying to do warrants calculating the molecular weights of fatty acids and sodium (potassium) fatty acids. Since you raised this question, it’s likely that you are dealing with waste oils of complex origin; for pure soybean oil or canola oil, whose fatty acid composition is well known, there is no need to ask such a question.