Natural Plant Extracts As Acid-Base Indicator
Natural Plant Extracts As Acid-Base Indicator
Natural Plant Extracts As Acid-Base Indicator
Many flowers, fruits, leaves, and roots contain chemical substances that change color in
different pH solutions. These chemicals are known as indicators. Indicators are chemical substances that
change colors when they come into contact with an acid or a base. In this experiment, some of these
indicators will be extracted. The pH's at which the indicators change color will be investigated.
Indicators are used mainly by scientists to test substances to see whether they are acidic or
basic. This is a safe way to determine whether a substance is an acid or a base. One example of an
indicator is litmus paper, which will simply tell you whether a substance is an acid or a base. But what if
we had two acidic substances? How could we tell which one was more acidic than the other? Litmus
paper will not work since it can only tell you that they are both acids. A universal indicator can be used
in this situation.
A universal indicator will undergo a variety of color changes in different pH solutions. It changes
color according to the pH of the material it is in. It is so helpful because the color also tells you how
strong the substance is. e.g., if you were to put a few drops of the indicator in water, it would turn
green. A few drops of it in detergent, and it would turn a deep purple.
Learning Outcomes:
1. Explain the stages involved in the preparation of natural indicators from plant parts,
2. Outline the steps involved in the extraction of indicators from the plant.
3. Explain the cause of the color changes in each of the solutions.
4. Identify and describe some everyday uses of indicators.
Materials:
• Turmeric
• Bougainvillea
• Mango leaves
• 70% isopropyl alcohol (or any rubbing alcohol available)
• Clear containers (plastic cups will do)
• Bleach
• Detergent
• Medicine dropper
Procedure:
1. Select a suitable colored plant material such as turmeric, Bougainvillea, Mango leaves.
2. Extract the color from the plant material by crushing it alcohol using mortar ang pestle.
Assessment Questions:
1. What caused the color changes in each of the solutions?
2. Outline the steps involved in the extraction of indicator from the plant.
3. How do indicators from the different materials differ from each other?
4. Explain what caused the color changes in each of the solutions.
5. Mention the principles involved in extracting natural indicators from natural sources.
6. Describe some everyday uses of indicators.
References:
Acid-Base Indicators. (2015, January 18). Retrieved April 18, 2021, from Chemistry LibreTexts
website:
https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_General_Chemistry_(Petr
ucci_et_al.)/17%3A_Additional_Aspects_of_Acid-Base_Equilibria/17.3%3A_Acid-Base_Indicators
Kapilraj, N., Keerthanan, S., & Sithambaresan, M. (2019). Natural Plant Extracts as Acid-Base
Indicator and Determination of Their pKa Value. Journal of Chemistry, 2019, 1–6.
https://doi.org/10.1155/2019/2031342
Sweta Garg, Ashish Garg, Pratha Shukla, & Souvik Sen. (2018). INVESTIGATION OF PLANT SOURCE
AS NATURAL INDICATORS FOR ACID BASE TITRATION TO REDUCE THE USE OF HARMFUL...
Retrieved April 18, 2021, from ResearchGate website:
https://www.researchgate.net/publication/324570322_INVESTIGATION_OF_PLANT_SOURCE_AS
_NATURAL_INDICATORS_FOR_ACID_BASE_TITRATION_TO_REDUCE_THE_USE_OF_HARMFUL_CH
EMICALS_IN_SOME_EXTENT