EXP 19

• Soaps are potassium or sodium salts of fatty acids.
• Soap making involves the hydrolysis of a triglyceride (fat or oil) using an alkaline solution usually lye,
• lye, chemical name sodium hydroxide.
• Triglycerides are typically triesters consisting of 3 long-chain aliphatic carboxylic acid chains appended to a single glycerol molecule.
• This process of making soap is known as saponification.
• The common procedure involves heating animal fat or vegetable oil in lye (sodium hydroxide), therefore hydrolyzing it into carboxylate salts (from the combination of carboxylic acid chains with the cations of the hydroxide compound) and glycerol.
• Sodium hydroxide can saponify oils.
• That means it helps the oils and fats lather and foam into a soap.
• It’s also used in small amounts to establish and maintain the pH of a product.
• Skin tends to be on the acidic side and usually ranges between 4 and 7.
• Maintaining this acidity (aka the “acid mantle”) provides a layer of protection against environmental factors like allergens, pollutants, and bacteria.
• Too much NaOH in soap formulation can cause skin symptoms like mild to severe chemical burns, or holes in the skin and underlying tissues.
• But it’s used in small amounts in skin care products like soaps that tend to get totally used up in the reaction process.
• One way to determine the amount of NaOH in commercial soaps is to perform a volumetric analysis.
• alkali is titrated with a standard acid solution (alkalimetry)
• the indicators to be used are either Methyl orange (M.O.) or Methyl Red (M.R.).