Acids, Bases, Buffers and Respiration
Darlene E. McDonald
WCCC Fall 2012
Ap Lab 071-07
Dr. Roxanne Levandosky
August 31, 2012
a. To define and understand the key terms.
b. To determine the acidic or base nature and actual pH of various substances.
c. To discuss the formation of the carbonic acid/bicarbonate ion buffer system in maintaining
homeostasis, especially with regard to ventilation.
Homeostasis is the tendency of a system, especially the physiological system of higher animals, to maintain internal stability, owing to the coordinated response of its parts to any situation or stimulus that would tend to disturb its normal condition or function. This is essential for the human life. Every piece of this experiment was to prove the slightest change can through your body off balance.
Acids are a subject that reacts to a base. A base is a substance that can accept hydrogen ions (protons). These two components together help the human body to stay balanced. The pH scale will help determine which direction the body is leaning towards; the base or the acid. The body has a buffering system to help regulate the process.
To help you better understand the pH in different substances please look at the below table. The pH of Some Common Substances
Increasing pH (Decreasing Acidity)
0 (most acidic)
| Hydrochloric acid (HCl)
| Stomach acid
| Lemon juice
| Cola, beer, vinegar
| Fish die if water is this acidic
| Normal rainwater
| Water, tears
| Human blood
| Baking soda, antacids
| Great Salt Lake
| Bicarbonate of soda
| Oven cleaner
14 (most basic)
| Sodium hydroxide (NaOH)
II. Materials and Methods
A. Materials for Part B
1. 3 small beakers
2. Distilled water
3. .1 M HCL
4. .1 M NaOH
5. pH meter
7. pH 7.00
8. pH 10.00
10. safety goggles
Materials for Part C
1. 2 beakers
2. .1 M NaOH
3. Distilled water
4. Phenolphthalein indicator
7. Test subject
9. Safety goggles
B. Method for part B
The experimenter obtained 3 beakers of distilled water. The said person then calibrated the distilled water to check the pH level. The second step was to add one drop of the .1M HCL to one the beakers and one drop of .1M NaOH to the other beaker, then stirred to ensure the solution was mixed. The experimenter then checked the pH value of each beaker using the pH meter and recorded the findings. The experiment continued by the addition of three drops of each solution into the correct beaker then pH was checked and recorded. The experiment continued 3 drops at a time until the maximum of 15 drops was obtained. This experiment was then continued using pH 7.0 and pH 10.0 in place of the distilled water. The results were checked and recorded.
The beakers were then emptied and cleaned out. The experiment area was then wiped down with the bac solution.
C. Method for part C
A beaker was filled with 200 mL of distilled water. 5.0 mL of .1M NaOH and a few drops of Phenolphthalein indicator. The solution was stirred and divided equally between 2 beakers.
The test subject was asked to sit and remain quite. The subject was then asked to blow through a straw into the solution of one of the beakers. The subject was asked to be careful not to let exhaled breathe escape the sides of the beaker. The time for all of the pink color in the solution to disappear was recorded.
Then the subject was asked to jog for 2-4 minutes. Immediately after the exercise the...
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