SBIOA/4UName: ___________________________________

ACIDS, BASES AND BUFFERS LAB

Instructions: (Record results in a table. Wear saftey glasses. Attach answers to Questions and Observations table to this sheet.)

  1. Prepare a table for your Observations (see overhead).

  2. Clean 5 test tubes thoroughly. Label them A, B, C, D, E and place them in a test tube stand.

  3. Make the buffer solution:
      Measure 15 mL of 0.1 M acetic acid solution into a graduated cylinder. Add 0.10 g. of sodium acetate to the graduated cylinder and swirl the mixture until the solid dissolves.

  4. Measure 5 mL of distilled water into test tube A and E only.

  5. Divide the buffer solution equally, 5 mL into test tubes B, C and D.

  6. Place a piece of pH paper in a clean watch glass or petri dish. Use a clean glass stiring rod to add a drop of solution A to the pH paper and record the initial pH of solution A. Continue for the rest of the solutions (B-E) washing and drying the stiring rod and watch glass/petri dish after each use.

  7. To test tubes A and B, add 5 mL of 0.1 M hydrochloric acid, gently swirl the solution, and test the pH again.

  8. To test tubes D and E, add 5 mL of 0.1 M sodium hydroxide, gently swirl the solution, and test the pH again.

Questions: (Answer fully on separate sheet.)

  1. What pH range is considered to be:
    a) acidic? b) basic? c) neutral?

  2. While working in a lab, an unknown chemical spill occurs. Explain the process and observations you would use to determine if the chemical is a(n):
    a) acid? b) base?

  3. Assuming that the chemical spill above was potassium hydroxide. What acid could you add to neutralize the base and what would the products be?

  4. Compare the initial and final pH in test tube A and B. What was the effect of the buffer?

  5. Compare the initial and final pH in test tube D and E. What was the effect of the buffer?

  6. What was the purpose of test tube C?

  7. Refer to pg. 742, "Acid-Base Balance", in your text. Write the reaction for the bicarbonate-carbon dioxide buffer system and briefly explain how it works in the case of a patient experiencing acidosis (too much acid).