Chem Lab 31

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Chem Lab 31
2010-03-25 00:15:32

Making Soap
Show Answers:

  1. A ___ is the sodium or potassium salt of a long-chain fatty acid.
  2. Most solid soaps are ____ salts.
  3. The starting materials are fats or oils, which are the ______ of the fatty acids.
    Glycerol esters
  4. What are the princple reactants in this experiment?
    Cottonseed oil (a typical cooking oil) and a concentrated solution of sodium hydroxide
  5. _____ is used in this experiment to serve as a common solvent for the reactants and hence to speed up the reaction.
  6. Is ethanol is used in commerical soap-making operations?
  7. What is soap making called?
  8. What is the saponification reaction in this experiment?
    oil -> glycerol + sodium salt
  9. The sodium salts of the long-chain fatty acids are typical ____ agents.
  10. Soap has a polar end which is _______ and a long nonpolar chain which is _______.
    hydrophilic; hydrophobic
  11. As consequence of soap's nonpolar and polar ends, they can form ______ by suspending oil in water when their nonpolar end is in the oil and their polar end group is in water.
  12. The _____ of kerosene in water by means of soap is done via emulsions.
  13. What are 3 common metal salts that can form insoluble precipitates with the long-chain fatty acids?
    Calcium, magnesium, and iron
  14. Hard water kills soap; what is "hard water"?
    water containing appreciable amounts of dissolved calcium, magnesium, or iron salts
  15. State on safety precaution to be taken when using (1) sodium hydroxide solution, and (2) ethanol.
    (1) wear safety glasses, (2) be careful around flames
  16. Describe how to determine safely if all ethanol has evaporated from the reaction mixture.
    Wait until the alcohol smell has disappeared
  17. What class of natural compounds serves as the starting material for the prepartion of soap when reacted with NaOH?
    the glycerol esters of fatty acids (fats and oils)
  18. How is the soap recovered as a solid product from the solution containing the other products of the reaction?
    Using the process called "salting out", which involves mixing the saturated sodium chloride solution into the soap prepartion.