chem 2

• Soda Ash is a technical grade anhydrous sodium carbonate (Na2CO3)
• Soda Ash is likely to contain from a small to moderate amounts of impurities such as chlorides and hydroxides
• Some of these impurities, notably the hydroxide, combined with acids, contribute to the total alkaline strength of the ash so that a simple titration analysis like the following does not necessarily give the true of percent (%) percentage of sodium carbonate but merely expresses the total alkalinity in terms of Na.CO,
• Products that can be analyzed by the same alkalimetric process as soda ash


  • Pearl ash (K:CO)
  • Limestone (CaCO)
  • Quicklime (CaCO3)
  • Washing soda (Na:CO3.10H2O)
  • Caustic Soda (NaOH)
  • Caustic potash (KOH)
  • Milk of Magnesia [suspension of Mg(OH)2]
  • Household ammonia (NH3)
• Alkalimetry


  The process where a strong alkali is titrated with a strong acid
• Indicators used in alkalimetry


  Methyl orange (M.O.) or Methyl Red (M.R.)
• Phenolphthalein and most other indicators are affected by the carbonic acid liberated in the reaction, which causes a change in color before the reaction is complete
• Soaps are potassium or sodium salts of fatty acids
• Soap making


  1. Hydrolysis of a triglyceride (fat or oil) using an alkaline solution usually lye, chemical name sodium hydroxide

  2. Triglycerides are typically triesters consisting of 3 long-chain aliphatic carboxylic acid chains appended to a single glycerol molecule

  3. This process is known as saponification
• Sodium hydroxide can saponify oils, helping the oils and fats lather and foam into a soap
• Without sodium hydroxide, the soap would be a big mess of various oils and fats that aren't unified into one product
• Sodium hydroxide is 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
• The amount of sodium hydroxide used in the manufacture of commercial soaps should be regulated
• 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 sodium hydroxide is used in small amounts in skin care products like soaps that tend to get totally used up in the reaction process, so a lot of it doesn't actually make it to the final product
• One way to determine the amount of NaOH in commercial soaps is to perform a volumetric analysis, specifically an Alkalimetric titration
• Alkalimetric titration


  The process where an unknown concentration of an alkali is titrated with a standard acid solution
• The indicators to be used in alkalimetric titration are either Methyl orange (M.O.) or Methyl Red (M.R.)
• This activity will make use of methyl orange indicator