Cherries as a Natural Indicator

Annie Sloan, Emily Shapiro, Nicole Pearlstein, Chloe Gitlin

Introduction

The purpose of this lab was to make our own indicator and be able to estimate the pH of various substances. We used cherries as our indicator. An indicator is a substance that turns different colors in solutions of different pH levels in presence of an acid or a base. The reason for the color change is that indicators chemically react with hydrogen or hydroxide ions to produce a specific color. Every indicator has a unique color and has a specific range of pH in which the color can change. The different types of ions are formed from acids and bases. An acid is a substance that when put in water dissociates to create hydrogen ions and anions. A base is a substance that when put in water dissociates to create hydroxide ions and cations. Referring back to our lab, we had to gather different household substances in order to predict whether they were acids or bases. The substances we used were bleach, vinegar, urine gone and lysol. Before the experiment took place, we predicted that vinegar and lysol would be acids and the other two would be bases.
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Cherry Indicator

Our liquid cherry indicator was made by blending real cherries in a blender.

Procedure

We determined the color range for our indicator by using known pH substances of 1,3,4,5,7,9,11,13. These were used for comparison to our household substances. Then, we added our indicator to the household substances in order to get the pH levels. We compared the color of the household substances to the known pH levels in order to predict the pH of the household substances and whether they were an acid or base.
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Data Table

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Colors of each Household Substance tested with Indicator

from left to right,

bleach: brown, pH 14

vinegar: cherry red, pH 3

lysol: smashed blueberry, pH 11

urine gone: eggplant, pH 10

Conclusion

While using cherries as an indicator, different colors resulted depending on the pH standards we tested. First we mixed the know pH acids with the cherries which resulted in different shades of red. Then we mixed the known pH bases with the cherries, and we got different shades of blue and green. When we tested the known pH of 7, which is neutral, it resulted in a lighter blue color. After we tested the pH standards, we tested household substances which we could then compare to the shades of the pH standards. First we mixed the cherries with bleach, and concluded it was a pH of 14 because it turned brown which is a dark brown. Then we mixed the cherries with vinegar, and concluded it was a pH of 3 because it turned cherry red. The third substance we mixed with the cherries was urine gone, which turned a deep purple and we concluded it had a pH of 10. The last substance we mixed with cherries was Lysol which turned dark blue and had a pH of 11. In conclusion, we determined that our natural indicator is better at detecting acids. When mixed with the cherries, the acids were easier to compare to the pH scale because more distinct colors were formed.The bases colors varied and were not within the same color range. Some problems we encountered when using cherries as a natural indicator were varying colors that didn’t match up with the pH scale. When we tested our natural indicator with the household substances, some colors occurred like brown and deep purple. These colors were difficult to analyze because they were out of the pH range of colors. If we were to redo this experiment, we would make sure we measured precisely the amount of drops of each pH and indicator to make the results more accurate and consistent.

Works Cited

Labs Used:

Properties of Acids and Bases

Red Cabbage as a Natural Indicator