Question

Explain the chemical nature of storage fats in the body. How are they stored (chemically), where are they stored (biologically). Explain the diversity in this group of molecules. Give a short historical perspective on saponification reaction and how it was used, starting supplies, etc.

Why are the fatty acids referred to as salts? Which takes more NaOH for complete saponification, 27 grams of olive oil, butter or lard? Since the same amount of NaOH, which soap should be more basic? Why?
Discuss why fatty acid salts can act as soaps.
Discuss the disadvantages of natural soaps.

Answer 1

1)Storage fats in the body are stored as triglycerides ,esters of glycerol and fatty acids.This is how they are stored chemically in the body in adipocytes or fat cells beneath the skin.Fats makeup the cell membrane bilipid double layer of those cells,

2)Saponification is the making of soap,or sodium /potasium salt of long chain fatty acids ,so it is prepared when fats are reacted with strong base sodium or potassium hydroxide.

Fats+NaOH --> Sodium salt of fatty acid +glycerol

3) Fatty acids with their carboxyl group -COOH having its H+ being replaced by Na+ or K+ cation forms a salt of fatty acid ,as it is a neutralization reaction of acid and base NaOH/KOH forming salt.

4) NaOH reacts with fatty acid in 1:1 molar ratio.

So, 27 grams of olive oil=27grams/molar mass of olive oil(oleic acid )

27 grams of butter=27grams/molar mass of butter(oleic acid+myristic acid+palmitic +stearic acid )

27 grams lard=27 g/molar mass of lard(palmitic+stearic+oleic+linoleic acid)

Almost same number of moles of fatty acids are present so same molar amount of NaOH required for saponification.Soaps will be equally basic as the fatty acid content is the same for the fatty acid salt