Organisms, pH, and Buffers -- October, 2002



Teacher Hints:

  1. "Recipes" for test solutions:

    • Liver homogenate or potato homogenate: blend 10 g / 100 mL of water
    • Egg white: dilute 1:5 with water
    • Gelatin: use 2% solution; keep warm to avoid setting

  2. Recipe for standard 0.01 M sodium phosphate buffer solution, neutral pH (7.2):

    • Create ‘solution A’ by dissolving 1.38 grams NaH2PO4 in 1 L distilled water.
    • Create ‘solution B’ by dissolving 1.42 grams Na2HPO4 in 1 L distilled water.
    • For buffer solution, mix 280 mL solution ‘A’ with 720 mL solution ‘B’; adjust pH as needed.

  3. To be more time-efficient, consider assigning different test solutions to different lab groups and comparing data as a class later on.