Answer to Question #208534 in General Chemistry for neil

Question

Animal fats and vegetable oils are triacylglycerols, or triesters, formed from the reaction of glycerol (1, 2, 3-propanetriol) with three long-chain fatty acids. One of the methods used to characterize a fat or an oil is a determination of its saponification number. When treated with boiling aqueous KOH, an ester is saponified into the parent alcohol and fatty acids (as carboxylate ions). The saponification number is the number of milligrams of KOH required to saponify 1.000 g of the fat or oil. In a typical analysis, a 2.085-g sample of butter is added to 25.00 mL of 0.5131 M KOH. After saponification is complete, the excess KOH is back titrated with 10.26 mL of 0.5000 M HCl. What is the saponification number for this sample of butter?

Answer 1

The acidity of every sample based on Mass % of Oleic acid

M(C₁₈H₃₄O₂) = 0.2O85g

M(sample) = 10g

= M(C₁₈H₃₄O₂)/M(sample) × 100

= 0.2085/10 × 100

= 2.8%

= 18

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