Lab Acid Titration

Conclusion

In part 1, the different household substances were tested to obtain there pH value, ranged from 2 to 10. The vinegar and lemon juice had the lowest pH due to their acidity which it was expected, and the ammonia and toothpaste had the highest pH. In part 2, the juice of the red cabbage changed colors depending on the pH of the substance that were added. The purple cabbage juice became red-pink when it was in contact with acidic substances such as lemon juice or vinegar; and it became green while in contact with basic substances such as ammonia or toothpaste. After analyzing the results of this experiment it is possible to determine the pH of a solution based on the color change of the red cabbage juice because the colors change of the cabbage juice is the results of the change in its hydrogen ion concentration.

The natural substances also used (black tea, rhododendron flower extract, and grape juice) also have the indicating properties as the red cabbage juice, and such properties were tested. The rhododendron's pedals extract changed color when the pH was modified by adding an acid or a base solution. However, with the black tea experiment there was not a drastic color change such as the red cabbage juice, but the color shade did change. When adding the strong acid (vinegar) it altered the acidity of the black tea, so the color changed as an indication of this, and similar when the base was added. This behavior of the black tea was due to the influence of the concentration of hydrogen ions in the water. Overall, the experiment had interesting and natural ways to show how the variation of pH can be determined by observing the color change of substances that have the natural indicators. Lab 5C Acid-Base Indicators

Gracie Diaz & Tyler Nordlie

July 20, 2011

Chem& 163 A

Analysis

Table 1. Summary Table

Household Substances

pH

Color

Lemon Juice

2

hot pink

Vinegar

2

Pink

Aspirin

3

light blue

Carbonated water

4

same-diluted

Antacid