Beet Juice as a Natural Indicator

Emma, Natalie, Jamie, Colleen

Introduction

The purpose of this lab is to better understand how to measure pH values of various substances while enhancing lab skills regarding proper handling of chemistry tools and substances. An indicator is a very weak acid or base that changes color in the presence of chemicals with different pH values. They change colors because of the dissociation of H+ ions (Larsen, 2015). An acid is a chemical substance with a pH less than seven, that turns litmus paper red and has a sour taste. A base is a chemical substance with a pH value greater than seven, that turns litmus paper blue and has a bitter taste (Levin, 2003).


Substances tested:

  • Windex
  • Baking Soda
  • Lime Juice
  • Distilled White Vinegar


Predictions:

  • Windex will be a base.
  • Baking Soda will be a base.
  • Lime Juice will be an acid.
  • Distilled White Vinegar will be an acid.

Procedure

Data

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Initial Color of Indicator- Beet Juice

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Colors of Indicator with pH Standards- with corresponding colors

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Initial Colors of Household Substances (left to right)

(Initial color of indicator), Left to right: Beet Juice for testing, Vinegar, Lime Juice, Baking Soda, Windex


Estimated pH:

  • Vinegar: 5
  • Lime Juice: 3
  • Baking Soda: 9
  • Windex: 11

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Colors of Household Substances Tested with Indicator

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Conclusion

We learned that beets as a natural indicator create a pH with a variety of colors which shows us which household substances are acids or bases. Acids resulted in dark pink and bright red colors. Bases resulted in extremely dark red, violet, and yellow colors. Our indicator is much better at detecting bases because there was a large array of colors produced for the bases, while the acids were all similar in color. The colors of the bases varied from violet to yellow! A problem we had when we were using our natural indicator was that the colors of the acids with the beet juice were very similar so it was difficult to decipher which pH values the household substances were. Another problem we encountered was that we did not mix our baking powder and water solution enough, so it was difficult to get an accurate pH reading without doing a re-trial. If we were to repeat this experiment we would have shredded the beets before boiling the beats because we believe it would have resulted in a darker indicator color that would lead to more identifiable pH colors.

Works Cited

University of California Davis. Larsen, D. (2015). Acid and Base Indicators. Retrieved May 30th, 2015. from http://chemwiki.ucdavis.edu/Physical_Chemistry/Acids_and_Bases/Case_Studies/Acid_and_Base_Indicators

University Illinois Urbana Champaign. Levin, J. (2003). Acids Bases and pH Scale. Retrieved May 30th, 2015. from http://lrs.ed.uiuc.edu/students/erlinger/water/background/ph.html