Ph Level Lab Report

Distinction of pH levels of Orange Juice and Milk of Magnesia in comparison to Distilled Water
Cooper, A., Do, J., Francois, F., Olaleye, O. Lab Section LA: 06/20/2012

Introduction pH is the measurement of the concentration of hydrogen ions in a certain solution. Solutions or substances that have a higher concentration of hydrogen ions are considered acidic on the pH scale. Therefore, a solution with low concentration of hydrogen ions is basic on the pH scale.
The pH scale is a universal means of measuring pH. It ranges from 0-14, with 0-6 being acidic,
7 neutral and 8-14 basic. In this experiment, the rationale is that since the orange juice and the milk of magnesia are not pure orange juice, which is acidic, and pure milk of magnesia,
which is basic, then it is the same pH of water, thus the hypothesis is if orange juice and milk of magnesia have a pH 7, then it has the same pH level as distilled water. The aim of this experiment is to determine whether orange juice and milk of magnesia have a pH of 7 or near to 7.

Methods
Three 50 mL beakers were obtained. 22 mL of orange juice were measured and placed into one 50mL beaker. The pH meter was then calibrated with distilled water. After the calibration, the electrode was place in the orange juice.
The pH level was recorded and the electrode rinsed with distilled water and patted dry with a KimWipe. Next, 22 mL of milk of magnesia were measured and placed in a 50mL beaker. The electrode was placed in milk of magnesia and the pH level was recorded and the electrode rinsed with distilled water and patted dry with a KimWipe. Finally, 22 mL of distilled water was placed in a beaker. The electrode was placed in the beaker and the pH level was recorded and the electrode rinsed with distilled water and patted dry with a KimWipe. This method was repeated twice more for a total of 3 trials. Water was the control variable, while the dependent variable was measuring the pH levels of orange juice and milk of magnesia. And the independent variable was by using different
substances. Results
Figure 1
Figure 1
The average of orange juice, milk of magnesia, and distilled water after collecting data from all 3 trials are 4.31, 9.56, and 6.91, respectively.
After calculating the averages, the negative standard deviation of orange juice is -0.03 and the standard deviation is +0.04. Also, milk of magnesia had a standard deviation of +0.04 and water had a standard deviation of 0.02. Since our standard deviations had small values, we had small error bars. Following the results, orange juice had a pH levels within the acidic zone while milk of magnesia had pH levels within the basic zone while water maintained a neutral pH (Figure 1).

Discussion and Conclusion
The data from our experiment rejects the hypothesis. Of the data we collected, orange juice and milk of magnesia did not have a neutral pH like distilled water. Orange juice was shown to be moderately acidic, with pH averaging of 4.31, which it’s pH level not anywhere near 7. This is nearly 1000x higher in H+ concentration than the distilled water. Orange juice has an acid content that influenced the buffering capacity, thus orange juice have a low pH (Singh and Jindal). Also, milk of magnesia was shown to be moderately basic, with pH ranging from 9.55 to 9.59, which is higher than a pH of 7 (Hemingway, et al).
Literature
Hemingway, C.A., White, A.J., et al. Enamel Erosion in Dietary Acids: Inhibition by Food Proteins in
Vitro. Karger; 2010. Available from http://content.karger.com/ProdukteDB/produkte.asp?typ=pdf&doi=320984 Singh, S., Jindal, R. Evaluating the buffering capacity of various soft drinks, fruit juices and tea.
National Institutes of Health; 2010 Jul-Sept. Available from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2980607/