lesson 2

• Inorganic compounds


  Molecules, usually small and lack carbon and in which ionic bonds play an important role
• Organic compounds


  Always contain carbon and hydrogen. Large organic molecules include lipids, carbohydrates, proteins, and nucleic acids
• Carbon


  • Primarily the element that makes up organic compounds that living things are made of
  • Allows it to bond with itself and with other elements such as hydrogen, oxygen, and nitrogen to form complex structures
• Iodine Test for the Presence of Starch


  1. Add 10 drops of 0.1% starch solution into a test tube

  2. Blue-black color = positive presence
• Benedict's Test for the Presence of Sugars


  1. Put glucose to a depth of 1cm

  2. Add water to a depth of 5cm. Stir.

  3. Add 10 drops of Benedict's solution

  4. Heat the glucose-water solution over flame of an alcohol lamp. Gently shake the test tube as you heat the liquid to its boiling point.

  5. Reddish-orange=positive
• Biuret Test for the Presence of Proteins


  1. Place a small piece of boiled egg yolk(food sample) in a test tube

  2. Add 12 drops of water.

  3. Add 12 drops of 10% sodium hydroxide

  4. Add 3 drops of 0.5% copper sulfate.

  5. Light blue to dark violet
• Test for the Presence of Lipid


  1. Add a drop of your food sample/solution on a slide.

  2. Add one drop of Sudan III or IV solution. Mix well.

  3. Examine under LPO.

  4. Look for red droplets