pH Lab Experiment


Jeff Price

Biology 101- 011

Dr. Art Ellis

1 May 1997

Trident Technical College
Charleston, South Carolina 29423

pH Lab

Upon hypothesizing that stomach medicines are useful in neutralizing the acidic affects of beverages when used properly an experiment was designed to test this theory. The experiment incorporated the use of white grape juice to be the acid, Maalox as the antacid, and red cabbage juice as the pH indicator. A control group was also formulated by substituting distilled water for the antacids. After mixing the solutions in separate test tubes, any changes were recorded. These changes were the indicators for the pH level of the mixture. The tube containing white grape juice changed to a pink color (pH value 3). The tube containing Maalox changed to a greenish blue (pH value of 8). There was no change in the control group. Then when white grape juice and Maalox were tested, a blue color resulted (pH value of 7, neutral). Therefore, the experiment shows that antacids can be effective neutralizers with proper use and understanding of how they work.
“pH is the measurement of positive hydrogen ions (H+) in solution. A substance that has a high concentration of H+ is acidic. A substance that has a low concentration of H+ is basic (alkaline)” (Dickey, 1995). The measurements of pH are obtained through paper tests, machine measurements, or the use of other indicators. Most of these other indicators rely on a change in a mixtures color in order to determine the pH level of the substance. These colors have been coordinated with pH values. The pH values begin at 0 and run to 14. A pH value of 0-6 indicates an acidic solution. A pH value of 7 indicates a neutral substance and a pH value of 8-14 represents a base (Starr and Taggart, 1995). “The ability to measure pH has become important in the manufacture of foods, paper, and chemicals” (Altwicker and Micheal, 1985). In the following experiment, a pH comparison is made between beverages and stomach medicines. “Some studies suggest that antacids may be of no benefit or may actually be harmful to the user” (Graf, 1985). One hypothesizes is that stomach medicines are useful in neutralizing the acidic affects of beverages when used properly.
Materials and Methods:
The experiment was conducted using eight clean test tubes, parafilm, red cabbage juice, white grape juice, 7UP, Club Soda, Seltzer Water, Milk of Magnesia, Sodium Bicarbonate, and Maalox With a 5mL delivery pipet and a green pi-pump, 3mL of either a beverage or medicine was added to the test tubes. In the eighth test tube, 3 milliliters of white grape juice and Maalox were combined. The tubes were labeled accordingly and then placed in a holding rack. Using a clean 5mL pipet with pi-pump, 3mL of red cabbage juice was added to each of the eight solutions. Parafilm was used to cover the test tubes and then the mixture were lightly shaken.
The reaction (color) of each test tube solution of either beverage or stomach medicine was compared to the color spectrum. The pH values of each solution was then recorded. The following chart shows the pH value of each solution.
Beverage pH Medicine pH
White grape Juice 3 Milk of Magnesia 12
7UP 4 Sodium Bicarbonate 10
Club Soda 6 Maalox 8
Seltzer Water 5

Combination Solution
White grape juice/Maalox 7

The beverages used in this experiment fully represent the acidic end of the pH scale (6-0). Stomach medicines in this case, represent the base side of the scale (8-14). On the pH scale, 7 is neutral and thus white grape juice mixed with Maalox resulted in a pH of 7.
Discussion and Conclusion:
In this pH experiment, it is shown that antacids such as Maalox can be used effectively in neutralizing acidic stomach acid when used properly. There are variations in acidity in each and every beverage as shown in the chart. The closer a pH value of a beverage is to 7 (neutral), the less likely that someone will have and acidic stomach. Therefore, the less acidic the stomach condition, the less likely someone will need to use an antacid. There is justification to be concerned about harmful effects of misuse. Excessive amounts of antacids will cause the pH balance in the stomach to become basic in nature. If this is allowed to continue, too basic is just as harmful as to acidic. According to Starr and