natural indicators experiment at home

Onion Natural PH Indicator

Introduction: Onion Natural PH Indicator

We can easily make a pH natural indicator from red onion. I have also tested it with different acids and bases and uploaded a video at the end .

1x Red Onion Boiling water Acids and Bases for testing

(Acids- Citric acid, Lemon, Vinegar etc.)

(Bases- Window cleaner, Baking soda, Detergent etc.)

Step 1: Chop an Onion Into Small Slices

Step 2: Boil Some Water, and Add It to a Container

Step 3: Put the Sliced Onion in the Water and Let the Water Cool Down

Step 4: After Cooling Down, the Water Gets Coloured

Step 5: The PH Indicator Is Ready! Strain and Use It

The solution turns red when added to an acid, and turns green when added to a base. Darker the colour, the more is it acidic or basic

Step 6: Testing With Acids and Bases

Step 7: Acids and Bases I Used

Bases- 1,2,3

Acids- 4,5,6

1- Window Cleaner , Color changes to Green- pH 11

2- Baking soda , Color changes to Light Green- pH 8

3- Detergent , Color changes to Yellowish-Green-pH 10

4- Citric Acid , Color changes to Red-pH 2

5- Vinegar , Color changes faintly to Red-pH 3 (Depends on the type of vinegar)

6- Lemon , Color changes to Light Red-pH 2

Home and Garden pH Indicators

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There are many common household products and garden plants that can be used as pH indicators. Most plants contain pH-sensitive anthocyanins, making them perfect for testing acid and base levels. Many of these natural pH indicators exhibit a broad range of colors .

Plants You Can Use to Test pH Levels

The natural world has given us numerous plants, from beets to grapes to onions, that can be used to test the pH levels of a solution. These natural pH indicators include:

• Beets:  A very basic solution (high pH) will change the color of beets or beet juice from red to purple.
• Blackberries:  Blackberries, black currants, and black raspberries change from red in an acidic environment to blue or violet in a basic environment.
• Blueberries:  Blueberries are blue around pH 2.8-3.2, but turn red as the solution becomes even more acidic.
• Cherries:  Cherries and their juice are red in an acidic solution, but they turn blue to purple in a basic solution .
• Curry Powder:  Curry contains the pigment curcumin, which changes from yellow at pH 7.4 to red at pH 8.6.
• Delphinium Petals:  The anthocyanin delphinidin changes from bluish-red in an acidic solution to violet-blue in a basic solution.
• Geranium Petals:  Geraniums contain the anthocyanin pelargonidin, which changes from orange-red in an acidic solution to blue in a basic solution.
• Grapes:  Red and purple grapes contain multiple anthocyanins. Blue grapes contain a monoglucoside of malvidin, which changes from deep red in an acidic solution to violet in a basic solution.
• Horse Chestnut Leaves:  Soak horse chestnut leaves in alcohol to extract the fluorescent dye esculin. Esculin is colorless at pH 1.5 but becomes fluorescent blue at pH 2. Get the best effect by shining a black light on the indicator.
• Morning Glories:  Morning glories contain a pigment known as "heavenly blue anthocyanin," which changes from purplish-red at pH 6.6 to blue at pH 7.7.
• Onion:  Onions are olfactory indicators. You don't smell onions in strongly basic solutions. Red onion also changes from pale red in an acidic solution to green in a basic solution.
• Petunia Petals:  The anthocyanin petunin changes from reddish-purple in an acidic solution to violet in a basic solution.
• Poison Primrose: Primula sinensis has orange or blue flowers. The orange flowers contain a mixture of pelargonins. The blue flowers contain malvin, which turns from red to purple as a solution goes from acidic to basic.
• Purple Peonies:  Peonin changes from reddish-purple or magenta in an acidic solution to deep purple in a basic solution.
• Red (Purple) Cabbage :  Red cabbage contains a mixture of pigments used to indicate a wide pH range.
• Rose Petals:  The oxonium salt of cyanin turns from red to blue in a basic solution.
• Turmeric:  This spice contains a yellow pigment, curcumin, which changes from yellow at pH 7.4 to red at pH 8.6.

Household Chemicals That Are pH Indicators

If you don't have any of the materials above at hand, you can also use some common household chemicals to test pH levels . These include:

• Baking Soda:  Baking soda will fizz when added to an acidic solution such as vinegar, but will not fizz in an alkaline solution. The reaction doesn't readily reverse itself, so while baking soda can be used to test a solution, it can't be reused.
• Color-Changing Lipstick:  You'll need to test your color-changing lipstick to determine its pH range, but most cosmetics that change color respond to changes in pH (these are different from cosmetics that change color according to the angle of light).
• ExLax Tablets:  These tablets contain phenolphthalein, which is a pH indicator that is colorless in solutions more acidic than pH 8.3 and pink to deep red in solutions more basic than pH 9.
• Vanilla Extract:  Vanilla extract is an olfactory indicator. You can't smell the characteristic scent at high pHs because the molecule is in its ionic form.
• Washing Soda:  As with baking soda, washing soda fizzes in an acidic solution but not in a basic solution.
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Red Cabbage Indicator

Question to investigate

How can you use a red cabbage to test and classify substances?

Chemistry concepts

• Acids and bases are classes of materials that have different properties.
• Acid-base indicators change color depending on whether they are in acids or bases.
• Red cabbage leaves contain a substance called anthocyanin that changes color depending on whether mixed with an acid or a base.

Activity logistics

• Ages : As written, this activity is suited for ages 8–12.
• Time : 45 minutes–1 hour
• Do not eat or drink any of the materials used in this activity.
• Work with an adult.
• Read and follow all directions for the activity.
• Read all warning labels.
• Wear Personal Protective Equipment (PPE), such as goggles, safety glasses, or gloves.
• Tie back long hair, roll up sleeves, and secure loose clothing.
• Be sure to clean up and dispose of materials properly when you are finished with an activity.
• Wash your hands well before and after the activity.

Disposal: Dispose of all solid waste in the trash. The liquids can be safely disposed of down the drain with plenty of water.

What you’ll need

• Red cabbage
• Fruit juice, for example: lemon, lime, orange, apple
• Soda pop (light-colored sodas work best)
• Liquid cleaning products (don’t use bleach)
• Solutions made by dissolving a solid such as baking soda, detergent, or baking powder in water
• Zip-closing plastic bag
• Dropper or straw
• Several small cups (one for each test)
• Small bowl or cup
• Measuring cups
• Measuring spoons

* You can use a straw as a dropper. First, dip the straw into the liquid. Place a finger over the top of the straw to make a seal. When you remove the straw from the liquid, the liquid will remain inside the straw. When you are ready to release the liquid, remove your finger from the top of the straw.

Make red cabbage indicator

• Tear several leaves of red cabbage into small pieces and place into zip-closing plastic bag.
• Add about a cup of water to the bag. Remove as much air as possible from the bag and seal it.
• Hold the bag at the top with one hand and squish the leaves in the water with the other hand for a couple of minutes until the water turns a dark blue.
• Pour the liquid from the plastic bag into a cup. Discard the leaves. The liquid is your red cabbage indicator.

Test various household solutions

Your red cabbage indicator should be dark blue in color. The color of the cabbage indicator will change to red or pink if the solution is an acid and it will change to green or yellow if it is a base. It will remain purple or blue if the test solution is neutral.

• Add about 1 tablespoon of the indicator liquid to a small cup.
• Use a dropper or straw to place several drops of the test liquid into the cup with the indicator.
• Record the color of the liquid in the cup below.
• To test another item, use a clean cup and fresh indicator liquid. Repeat steps 4-6.
• In the table in the printable PDF, record the item, the color the liquid turns, and if it is an acid, a base, or neutral.

What did you observe?

Download this worksheet to record your observations.

How does it work?

Chemists classify substances as acids or bases . Lemon juice and vinegar are both examples of acids. On the other end of the spectrum are bases. An example of a base is baking soda, which you might have used in the kitchen to make cookies and cakes. Many soaps are bases. Some substances are neutral , meaning they are neither an acid nor a base, like water.

How can you tell if something is an acid or a base? Acids and bases can change the color of substances called acid-base indicators .

Red cabbage contains a chemical called anthocyanin . This pigment is a natural acid-base indicator. It is blue in neutral substances, like plain water. When an acid like lemon juice gets in the water, a reaction makes the indicator molecule change shape and it looks pink. When instead a base gets in the water, a different reaction happens that changes the indicator molecule and it looks green.

This activity is adapted from an activity that originally appeared in the Celebrating Chemistry issue for Chemists Celebrate Earth Day 2010.

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Color-Changing Liquid

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How to Make an Indicator for Acids and Bases Using Hibiscus Petals

Last Updated: October 20, 2021 References

This article was reviewed by Anne Schmidt and by wikiHow staff writer, Hannah Madden . Anne Schmidt is a Chemistry Instructor in Wisconsin. Anne has been teaching high school chemistry for over 20 years and is passionate about providing accessible and educational chemistry content. She has over 9,000 subscribers to her educational chemistry YouTube channel. She has presented at the American Association of Chemistry Teachers (AATC) and was an Adjunct General Chemistry Instructor at Northeast Wisconsin Technical College. Anne was published in the Journal of Chemical Education as a Co-Author, has an article in ChemEdX, and has presented twice and was published with the AACT. Anne has a BS in Chemistry from the University of Wisconsin, Oshkosh, and an MA in Secondary Education and Teaching from Viterbo University. This article has been viewed 146,916 times.

If you’re looking for a fun science experiment to do at home, making an indicator solution might be the perfect project. By mixing dried hibiscus leaves and water, you can make a cheap and sensitive chemical indicator for bases and acids in just a few minutes. After that, you can go wild with testing household items to see where they fall on the pH scale.

Combine your dried hibiscus petals with water.

• If you gathered your own hibiscus flowers, gently pluck off the petals and spread them out on a paper towel. Leave the petals in the sun for 2 to 3 days until the leaves look crispy and slightly brown.

Boil the mixture for 3 to 5 minutes.

• No need to stir your mixture—just sit back and relax.

Cool the mixture for 5 to 10 minutes.

• If you pour the liquid too early, you might end up with a chunky, lumpy indicator.

Pour the liquid into a clean beaker.

• The liquid will be a deep red color, but you should still be able to see light shining through it.

Mix your chemical with water in a test tube.

• The substance you choose is up to you, but people often use salt, window cleaner, orange juice, apple juice, or toilet bowl cleaner.

Add 4 to 5 drops of hibiscus indicator to the tube.

• Hibiscus flowers contain the colour pigment anthocyanin, which is a natural chemical indicator.

Check the color change of the water.

• Dark pink: pH 2
• Pink: pH 3 to pH 4
• Pale pink: pH 5
• Lavender: pH 6
• Gray: pH 7 or pH 8
• Dark gray: pH 9
• Brown: pH 10 or pH 11
• Green: pH 12

Expert Q&A

Things You’ll Need

• 2 to 3 grams of dried hibiscus petals
• 150 mL beaker
• Bunsen burner or a hot plate
• 100 mL beaker
• 1 tsp (5.6 g) of a chemical of your choice

You Might Also Like

• ↑ https://www.flinnsci.com/api/library/Download/75bfca43b9da4346a173bf3ac21fd68a
• ↑ https://www.youtube.com/watch?v=-V5LJ9O9LBU&t=49s
• ↑ https://www.scholarsresearchlibrary.com/articles/extraction-of-the-cyanidin3sophoroside-from-hibiscus-rosasinensis-an-efficient-natural-indicator-over-a-wide-range-of-acidbase-tit-12313.html
• ↑ https://www.youtube.com/watch?t=95&v=-V5LJ9O9LBU&feature=youtu.be
• ↑ https://www.youtube.com/watch?v=6KMP2Foj93U&t=144s

About This Article

To make a fun pH indicator at home with hibiscus petals, place the petals in a heat-proof beaker or pan with water. Heat the water over a Bunsen burner or hot plate and let it boil for about 5 minutes, or until the water turns dark red. Let the mixture cool for 5 to 10 minutes, then gently pour it through a strainer to remove the petals. Pour the chemicals you’d like to test into individual test tubes, then add a few drops of the hibiscus dye into each tube. Watch the liquid change color depending on how acidic or basic it is. Read on to learn how to interpret the results of your pH indicator test! Did this summary help you? Yes No

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Turmeric pH Indicator Experiment for Acids & Bases

Turmeric pH Indicator Experiment for Acids & Bases

This turmeric pH indicator experiment for acids and bases is a fun, easy way to learn about acids and bases. If done with gentle household items like vinegar, lemon juice, baking soda, etc. it is safe even for young children.  

Turmeric is a natural pH indicator. It changes colour in the presence of acids and bases. In the presence of acids, turmeric remains yellow, but in the presence of alkaline substances (bases), it turns red. It is ideal to use it for doing experiments with vinegar or citric acid and baking soda.

pH and chemical reaction – A simple summary

The pH is the measure of how acidic or basic (alkaline) a substance is. It is represented in a numerical range from 0 to 14, with seven being neutral. The more acidic the material, the closer it is to 0, the more basic, the closer it is to 14.  The pH number indicates the presence or absence of hydrogen ions. Acids have hydrogen ions (H+), and bases have hydroxide ions (OH-). The higher the concentration of these ions, the more acidic or basic the substance. 

When an acid and base come in contact with one another, a chemical reaction occurs. Acids and bases neutralize one another by breaking apart and forming into new substances. The reaction always results in the creation of water (H2O) and a salt. 

If you want some more information about pH and colour changing experiments, you may want to see my Color pH Baking Soda and Vinegar Science Experiment .

What you need for a turmeric pH indicator experiment for acids and bases

• Baking soda/bicarbonate of soda
• Vinegar, lemon juice or citric acid
• Ice cube tray (optional)

There are different ways to do this experiment to make it exciting and fun for children. 

The simplest way is for children to add different substances to some turmeric to see what happens. They could test substances such as lemon juice, soda, baking soda, water, etc. to see which one cause turmeric to change colour.

Once they have explored using turmeric as an indicator, they can have some fun with it. One option is to take some baking soda and mix in some turmeric. I usually use 2-3 teaspoons of turmeric for every ½ cup of baking soda. You will also need to add in a few teaspoons of water to help mix it all together. Once it is well combined, spread it out on a tray. Children can then squirt lemon juice or vinegar onto it using a pipette to see what happens.

Alternatively, you can also try freezing the baking soda. 

To do this, prepare the turmeric, baking soda and water mixture as above. However, you may need to add a little more water to this mixture so that it will stick together. Scoop it into ice cube trays or moulds and place it in the freezer for several hours. 

Once it is frozen, children can place the frozen cubes in a plate or bowl full of vinegar or citric acid. Alternatively, they can squirt the cubes with vinegar to create a reaction.

Questions to ask

• What do you notice about the reaction?
• What happens to the turmeric when it comes into contact with different substances?
• Is there a difference when you freeze the bicarbonate of soda rather than leave it room temperature?
• What do you notice when you combine the baking soda and vinegar when the turmeric is present?
• Could you think of a way to prove that a new substance is created after the reaction? What could you do?
• What happened? Why do you think it happened? What did you learn?
• Is there anything more you would like to try out or test?

What they get from it

This experiment will help children to explore the changes in pH that occur as part of a chemical reaction. They may also begin to think about whether there might be other ways to demonstrate that new and different substances form as part of a chemical reaction. This hands-on activity will teach them to predict, observe, record and discuss, or present their findings. Doing experiments will provide children with an opportunity to write by recording their observations with notes or drawings. Children enjoy doing experiments, and it can be highly motivational to write, even for more reluctant writers.

Research shows that people learn best (for long-term memory at least) when they learn through hands-on, practical experiences. (Hearns, Miller & Nelson, 2009; Hillman, 2011; Ferri, B.H., Ferri, A.A., Majerich, D.M., Madden, A.G., 2016). It’s also an opportunity for children to begin to develop scientific thinking. Furthermore, inquiry-based learning will encourage children’s curiosity and love of learning. (Ambrose et al. 2010; Froyd 2008; Prince & Felder, 2007; Springer, Stanne & Donovan, 1999). 

Take it further

See my other vinegar and baking soda experiments so that children can explore chemical reactions: 

• Baking Soda and Vinegar Painting Experiment for Kids  (coming soon)
• Color pH Baking Soda and Vinegar Science Experiment  
• Colorful Baking Soda and Vinegar Experiment for Kids  
• Frozen Bicarbonate of Soda and Vinegar Experiment
• Valentines STEM Art Projects for Toddlers and Kids . 
• You may also want to see my post on pH (acid-base) indicators ( coming soon ).

It can be great for children to create their own experiments based on what they want to find out. Allow them to ask questions to extend their learning. Ask them: What questions do you have about these reactions? Can you design an experiment to answer one of the questions?

They may want to see if they can find the exact amount of vinegar to make the baking soda react. They might want to see if a frozen baking soda ball reacts faster with vinegar than a dried baking soda ball. Alternatively, they may want to see if there is a difference in the reaction between vinegar and citric acid. 

I hope that you enjoy trying out using turmeric as a pH Indicator in an experiment with acids & bases.

Ambrose, S. A., Bridges, M. W., DiPietro, M., Lovett, M. C., & Norman, M. K. (2010).  How learning works: Seven research-based principles for smart teaching . San Francisco, CA: Jossey-Bass.  https://books.google.com/books

Ferri, B.H., Ferri, A.A., Majerich, D.M., Madden, A.G. (2016). Effects of In-Class Hands-On Laboratories in a Large Enrollment, Multiple Section Blended Linear Circuits Course. Advances in Engineering Education, 5 (3).  https://files.eric.ed.gov/fulltext/EJ1121997.pdf

Froyd, J. E. (2008).  White paper on promising practices in undergraduate STEM education . Commissioned paper, Board on Science Education, National Academies. Retrieved from  https://sites.nationalacademies.org/DBASSE/BOSE/DBASSE_080106#.UUoV5hngJ8g

Hearns, M.K., Miller, B.K. and Nelson, D.L. (2009). Hands-On Learning versus Learning by Demonstration at Three Recall Points in University Students. OTJR: Occupation, Participation and Health, 30 (4), 169-171.  https://journals.sagepub.com/doi/10.3928/15394492-20090825-01

Hillman, C.N. (2011). The effects of hands-on learning versus learning by demonstration on memory in community-dwelling older adults (Doctoral dissertation, The University of Toledo). Retrieved from  https://pdfs.semanticscholar.org/6231/d55fc1c730ec086f012677c54141f466e18e.pdf

Prince, M., & Felder, R. (2007). The many facets of inductive teaching and learning.  Journal of College Science Teaching, 36 (5), 14–20.  https://s3.amazonaws.com/academia.edu.documents

Springer, L., Stanne, M. E., & Donovan, S. (1999). Measuring the success of small-group learning in college-level SMET teaching: A meta-analysis.  Review of Educational Research, 69 , 21–51.  http://archive.wceruw.org/cl1/CL/resource/scismet.pdf

Physics & Chemistry , Preschooler , School Age

Baking soda , bicarbonate of soda , chemical reaction , colour , learning outside , pH , science experiment , Vinegar

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Natural pH Indicator: Cabbage vs. Beets

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Natural pH indicators: Cabbage vs. Beets

Learn how to make your own natural ph indicators and the difference between using cabbage or beets as your indicator liquid plus its a ton of fun to see the colors change, great for little kids., project ingredients:.

• Beetroot juice and/or purple cabbage juice
• pH paper (as a control)
• Small pipettes
• Sample cups

First things first, how to make a pH indicator with beetroot:

It’s easy! Just boil the beets in water for 30-60 minutes.

The purple water acts as a natural pH indicator using beetroot! You can, of course, blend in mashed beets and filter out the beet flesh if you want a darker fluid, but just beets boiled in water works great. You can also purchase beetroot juice that will work straight from the bottle!

How to make a pH indicator with purple cabbage:

Similar to making the beetroot indicator, you’ll need to cut up the purple cabbage and boil it for 30-60 minutes. Yet again, the purple liquid will act as a natural pH indicator!

How well do beets work as a natural pH indicator?

Looking at natural pH indicators is a fun way to bring chemistry home. Kids will enjoy mixing and testing all sorts of household items. We got pH paper , little pipettes , and sample cups to make the activity that much more fun. You can also use the pH paper to check your results! You can see our beetroot pH color table and cabbage pH color table below.

Beets, blackberries, grape juice, plums, turnip skin, and more all act as an edible natural pH indicator.

They all have anthocyanin in them which makes the solution change color, but they also differ in that little side groups attached to the main molecule cause the color changes to vary between foods. We talked a lot about how the chemical structure of anthocyanin changes the color of the solution in our post about purple cabbage as a natural pH indicator.  

You should also check out our post explaining what is a pH indicator .

I took a look at beet juice (on the top row) and compared it to our control of red cabbage (bottom).

The beets did a great job detecting our very basic drain cleaner which turned it yellow, but the color changes between baking soda and citric acid are difficult to see. The solution was mainly a purplish red the whole time.

This doesn’t bode well if you are looking to test the acidity of a substance more finely than just pH 13 and pH<13!

The purple cabbag e lab , of course, went through a variety of colors. Dark green and brown for the  drain cleaner , purple-blue for baking soda, purple with water, pink with vinegar and red with  citric acid . This gives us a much better idea of an actual pH value when testing things. Of course, if you are just looking to test extreme bases, the beet juice would work just as well!

You can also compare your tests to  pH paper  dipped in the various solutions as a guide.

Purple cabbages are as easy to find at the store as beetroot, so while you can make a pH indicator using beetroot, I suggest using purple cabbage instead as you get a better range of distinct colors as the pH changes.

It was so much fun comparing these two natural pH indicators, I can’t wait until blackberry season hits so we can do it again with blackberry juice! What natural pH indicators do you want to try?

Natural pH indicators:

• Purple cabbage
• Blackberries
• Blueberries
• Cranberries

Update : We got around to using crushed blackberries which do change color, but do not have nearly as good of a range as beets or red cabbage. We have also tried cranberry juice which is great to use as a secret invisible ink revealer. And lastly, during a bout of the plague in our house, we were drinking a ton of  turmeric tea . At one point when I added some lemon juice to the tea it completely changed color , which was a really fun way to talk about this project and the chemistry of acids and bases once again!

Try testing some other natural pH indicators with your kids and find your favorite! Make sure to send us your photos of your fun science projects as you become STEM Explorers! You can download our Cabbage pH lab book below for FREE to get a taste of our approach to homeschool science curriculum. We also have tons of free mini maker activities and premium labs to fill up your days with hands-on, inquiry-based STEM learning!

Check out our other fun science activities!

11 thoughts on “Natural pH Indicator: Cabbage vs. Beets”

Hey Erica, it’s Fanny. I did the lab with Nandu and my neighbor kids today and we actually got a good yellow with drain cleaner on red cabbage juice. So I guess it’s also possible 🙂

Thanks for entertaining us on a rainy Saturday afternoon.

Nice!! We got yellow with bleach on the cabbage juice, maybe I have the less effective drain cleaner…which could be why it never works quite right!!

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Making a pH indicator using red cabbage

In association with Nuffield Foundation

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Try this class practical to make a pH indicator from red cabbage with your students

A pH indicator is a substance which has one colour when added to an acidic solution and a different colour when added to an alkaline solution. Various colouring materials in plants can act as indicators. In this practical, students make an indicator from red cabbage.

The experiment is in two parts. In the first part, students boil some red cabbage in water. In the second part, they test their indicator. Between the two parts the mixture must be allowed to cool. The first part takes about 10–15 minutes. The cooling takes about 15 minutes and the testing less than five minutes.

The cooling period could be used as an opportunity to discuss the background to the experiment – see Teaching notes below.

• Eye protection
• Beaker, 250 cm 3
• Bunsen burner
• Heat resistant mat
• Test tubes, x3 (small test tubes of about 10 cm 3 are ideal)
• Test tube rack
• Dropper pipette
• Several pieces of red cabbage

Students will need access to:

• Dilute hydrochloric acid, 0.01 M
• Sodium hydroxide solution, 0.01 M
• Deionised or distilled water

Health, safety and technical notes

• Read our standard health and safety guidance.
• Wear eye protection throughout. Consider clamping the beaker.
• Each group of students will need access to the hydrochloric acid and sodium hydroxide solutions, and to deionised or distilled water. Provide all three in similar containers labelled ‘Acid’, ‘Alkali’ and ‘Water’. Dropper bottles are ideal. Alternatively small beakers (100 cm 3 ) with dropper pipettes could be used. Students need to be able to pour the acid and alkali solutions easily and safely into test tubes.
• Dilute hydrochloric acid, HCl(aq) – see CLEAPSS Hazcard HC047a .
• Sodium hydroxide solution, NaOH(aq) – see CLEAPSS Hazcard HC091a .

Source: Royal Society of Chemistry

The equipment students will need for making a pH indicator using red cabbage

• Boil about 50 cm 3  of water in a beaker.
• Add 3 or 4 small (5 cm) pieces of red cabbage to the boiling water.
• Continue to boil the red cabbage in the water for about 5 minutes. The water should turn blue or green.
• Turn off the Bunsen burner and allow the beaker to cool for a few minutes.
• Place 3 test tubes in a test tube rack. Half-fill one of the test tubes with acid, one with alkali, and one with distilled or deionised water. Label the test tubes.
• Use a dropper pipette to add a few drops of the cabbage solution to each test tube. Note the colour of the cabbage solution in each of the three test tubes.

Teaching notes

Discussion points could include any or all of the following:

• Many plant colouring materials in berries, leaves and petals act as indicators.
• Some of these will not dissolve in water easily. A solvent other than water (eg ethanol) could be used, but it may be flammable. Discuss how the risk of fire can be reduced by using a beaker of hot water to heat the mixture.
• Possible variations on this experiment might include using beetroot, blackberries, raspberries, copper beech leaves, or onion skins in place of the red cabbage.

Additional information

This is a resource from the  Practical Chemistry project , developed by the Nuffield Foundation and the Royal Society of Chemistry.

Practical Chemistry activities accompany  Practical Physics  and  Practical Biology .

© Nuffield Foundation and the Royal Society of Chemistry

• 11-14 years
• 14-16 years
• Practical experiments
• Acids and bases

Specification

• An indicator is normally used to show when the end-point is reached.
• (a) the properties of metals, ionic compounds, simple molecular covalent substances and giant covalent substances
• 8. Investigate reactions between acids and bases; use indicators and the pH scale
• pH scale. Use of universal indicator paper or solution. Limitations of the pH scale - usefulness confined to dilute aqueous solutions.
• Theory of acid-base indicators

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• Natural Indicators Around Us

We know about Acids and Bases  . But how do we determine whether a substance is acidic or basic? We have  Natural Indicators around us. You probably have a natural indicator in your home right now. Let us find out more about the natural indicators around us. 

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What are natural indicators.

Natural Indicator is a type of indicator that can be found naturally and can determine whether the substance is an acidic substance or a basic substance. Some examples of natural indicators are red cabbage, turmeric, grape juice, turnip skin, curry powder, cherries, beetroots, onion, tomato, etc.

Some flowers like hydrangeas can determine the acidity or basicity of the soil. These flowers become blue if the soil is acidic, purple if the soil is neutral and pink if the soil is basic. The intensity of the color depends on the amount of acid or base present in the soil. Soil which is highly acidic bears deep blue flowers, whereas soil which is highly basic yields deep pink flowers.

These natural indicators are used to detect the hydrogen ions (H+) and hydroxyl ions (OH-) in a solution. Olfactory indicators can change their odor. Some examples of olfactory indicators are onion, vanilla extract, clove oil, etc.

Browse more Topics under Acids Bases And Salts

• Acids and Bases
• Neutralization

Importance of Indicators

It is important to determine the nature of a substance because it is essential in biology, chemistry, civil engineering, water purification , agriculture, forestry, food science, environmental science, water treatment, oceanography, medicine, nutrition, agronomy, etc.

Even litmus is extracted from lichens. It is a water-soluble mixture of different dyes. It is then absorbed onto filter paper to produce one of the oldest forms of pH indicator, used to test materials for acidity or basicity.

Aim: Create a natural indicator using red cabbage.

Objective: To find out whether red cabbage is a natural indicator.

Experiment: 

• Chop some red cabbage and put it in a mixer or a blender.
• Add water to it and mix it until a juice is prepared.
• Strain this mixture into a glass.
• Take different substances like lemon, milk, vinegar, ammonia, bleach etc and mix it with the red cabbage solution.
• The color of the substance will change according to their acidity of basicity.

Observation: Acidic substances change the color of the solution from purple to red or pink. Neutral substances turn the purple solution to blue. Basic substances change the color of the purple solution to green or yellow.

Conclusion: Therefore,   we can say that   red cabbage is a natural indicator.

Question For You

Q1. What is the pH value of seawater? Is it acidic, basic or neutral in nature?

• less than two, it is highly acidic
• more than ten, it is highly basic
• between 7 – 8.5, it is neutral or slightly basic
• between 5.5. – 7, it is neutral or slightly acidic

Ans. The correct answer is option ‘b’. The value of seawater is between 7 to 8.4. Ideally, the sea water is neutral or slightly basic.

Q2. What is the pH level of the human body? Is it acidic, basic or neutral?

•  Less than 7, acidic
• More than 7, basic
• None of the above

Ans: The pH value of a normal body is ideally 7.4 which is on the alkaline side of neutral and human blood is usually between 7.35 to 7.45 and of human saliva is 7.5.

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• Neutralization Reaction

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Edible pH Indicators From Your Kitchen and Garden

Red cabbage juice is the best known edible pH indicator , but there are many safe fruits, vegetables, and flowers that change color in response to acidity or alkalinity. The plant pigments responsible for the color change are anthocyanins . Most of these molecules change from red to purple to blue in response to pH. Yellow, orange, and red are also possible.

Pretty much every berry changes color. The deeply colored skins of vegetables are also good. In addition to the plants listed in the table, try acai, currant, chokecherry, eggplant, colored corn, raspberry, and blackberry. Edible flowers that change color include violets , roses, hibiscus, and butterfly pea .

How to Use Edible pH Indicators

There are a couple of ways to extract the colors from the plants in a way you can use or save for science projects, natural Easter egg dyes, or for color change food colorants.

• Dry the flower, fruit or vegetable and then use a spice grinder to make a powder.
• Finely grate the plant. Soak it in a minimum amount of boiling water to extract the color. Extract the colored water (basically a concentrated tea) by wrapping it in cheesecloth or a coffee filter and squeezing it out. You can refrigerate the liquid to use within a week or freeze it for use within a couple of months.

Related Posts

Make Your Own Indicators

Testing the pH of a solution is a fundamental skill in chemistry. Students typically test pH using a pH meter, litmus or pH paper strips, or one of a variety of commercial acid-base indicator solutions. Acid-base indicators are weak organic acids that change color depending on the pH of a solution. A wide variety of pH indicators, such as phenolphthalein, methyl orange, phenol red, and bromthymol blue, can be purchased.

Effective pH indicators can also be made at home or in the classroom from items you probably already have in your kitchen or garden. Anthocyanins are a class of organic compounds found in many plants, fruits, and flowers that are red, blue, or purple in color and change color with pH. In this activity–a great introduction to pH for elementary and middle school students–you will extract anthocyanin pigment from plant material for use as a natural pH indicator.

Most of the indicators used in this activity come from plant pigments and will stain skin and clothing.

Materials (per class)

• Plant Material Containing Anthocyanins (red cabbage, blueberries or blackberries, and purple grape juice)
• Lemon Juice, Vinegar, and Baking Soda Solution (known acids and bases for testing)
• Light-Colored Liquids (unknowns for testing)
• Vegetable Peeler
• Strainer or Colander
• Small Cups or Beakers (to hold prepared indicators and solutions for testing)
• Disposable Pipets or Medicine Droppers

Preparation

• If performing the activity at home, clean the space to be used for the activity with household surface cleaner.
• Gather materials.
• Prepare the indicator solutions. For red cabbage : Add about ¼ cup of grated red cabbage to 2 cups of water in a small pan. Heat the water to a boil until the water turns purple. Strain the solution to remove any cabbage. For blueberries or blackberries : Place 2 to 3 berries in a small bowl and mash with a fork to make a paste, or use about a teaspoon of blueberry or blackberry jam. Add about 5 mL of water and stir, then strain to remove any solids. For grape juice : Be sure to use purple grape juice, as white grape juice will not work. The juice can be used as is from its container.
• Place a few milliliters of a known acid in a small cup or beaker.
• Add 1 or 2 drops of one of the prepared indicators.
• Record any color changes.
• Repeat the process using each of the indicators and known acids and bases to determine the color changes for the prepared indicators in the presence of acids and bases.
• Place a few milliliters of a liquid with an unknown pH, such as a light-colored soft drink, in a small cup or beaker.
• Add 1 or 2 drops of one of the prepared indicators to the solution.
• Use your observations to determine if the solution is an acid or base.

Students should find that most of the prepared indicators are red to purple in the presence of an acid, violet to blue at a neutral pH, and turquoise to green in a basic solution. Have students explore what other plant materials they can use as an indicator. A wide variety of plant materials containing anthocyanins will work as pH indicators. Additionally, turmeric (a spice) and some types of teas will also change colors in the presence of an acid or a base.

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Outside the Classroom: Edible pH Indicators in your Kitchen

• Outside the Classroom: Edible pH…

You may be familiar with the sour taste of a lemon but have you thought about why its tangy flavor packs such a sour punch?  Lemons are sour because they contain citric acid which is a weak organic acid found in many citrus fruits like oranges, lemons and limes.

In this At-Home Science experiment, aired on WJLA’s “ Outside the Classroom ” on May 1, 2020, Learning Undefeated VP of Communications Janeé Pelletier demonstrates how red cabbage juice can be used as a pH indicator to determine whether certain liquids are an acid or a base.  Red cabbage juice is usually a deep dark purple color but it turns red when added to an acid or green when added to a base. Red cabbage juices is the best known edible pH indicator in your kitchen but there are many safe fruits, vegetables and flowers that change color in response to acids and bases such as eggplant, beets, blueberries, cherries, onion, raspberry, grape juice, turmeric, and even tomatoes! 

Check out our At-Home Science page for full instructions and a downloadable laboratory protocol for this experiment!

Related posts

DIY pH Indicators: Turn Your Kitchen Into a Chemistry Lab!

Experiments, may 27, 2020.

Turn your kitchen into a chemistry lab by making your own DIY pH Indicators!

pH   is a measurement of how acidic or basic something is on a scale of 0-14.  

Testing how acidic or basic something is with a color-changing indicator is a staple of many chemistry experiments. Now you can try it too! Turn your kitchen into a chemistry lab with DIY pH indicators!

A substance with a pH of 7 (like distilled water) is  neutral . A substance with a pH of less than 7 is an  acid . The closer the number gets to zero, the stronger the acid is. A substance with a pH of more than 7 is a  base . The closer the number is to 14, the stronger the base is.

Try making one of these two natural DIY pH indicators and use it to test the pH of things you find around your home!

Recommend Age: 8+ with adult help for chopping and boiling.

Materials you will need for a red cabbage pH indicator:

• Red cabbage
• Knife and cutting board
• Strainer or funnel with coffee filter
• Container to collect indicator

WARNING: Cabbage and blueberry juices can stain clothes! Mess-friendly play clothes or coverings such as aprons are recommended for this activity.

Directions for making red cabbage pH indicator:

• Peel 3 or 4 big leaves off a head of red cabbage and chop the leaves into small pieces.
• Fill a blender halfway with hot water.
• Add the chopped cabbage leaves to the blender.

*Alternatively, you can boil the chopped leaves in just enough water to cover them for a few minutes, then let steep for 30-60 minutes.

STEP 2 

• Place a strainer or funnel lined with a coffee filter over a container to collect the indictor, such as bowl, pot, or bottle.
• Pour the mixture through the strainer to remove the cabbage pulp.
• Push down on the pulp in the strainer with a spoon or spatula to squeeze out more liquid.
• The purple liquid in your container is your indicator solution. The exact color will vary depending on the pH of the water you used.
• Experiment with the indicator using the ideas below!
• Red cabbage indicator can be saved in a sealed container in the refrigerator for up to 1 week.

Materials you will need for a blueberry pH indicator:

• 200g blueberries
• Masher, spoon, or spatula to mash blueberries

Directions for making blueberry pH indicator:

• Mash the blueberries in a bowl or pot to release the blueberry juice.
• Add mashed blueberries, juice, and a half cup of water to a pot.
• Boil the blueberries for 5-10 minutes. The blueberry juice will turn red-purple.
• Place a strainer or funnel lined with a coffee filter over a container to collect the indictor.
• Pour the mixture through the strainer to remove the blueberry skins.
• Push down on the skins in the strainer with a spoon or spatula to squeeze out more liquid.

What to do with your DIY pH indicators 

Now that you have your pH indicators, it's time to get to testing! Use household liquids such as salt or distilled water, different fruit juices, milk, liquid detergent or soap, and more!

• Add each of the substances you would like to test to the cups. (Only add one substance to each cup.) 
• Add a spoonful of indicator to the first cup, and stir the indicator into the substance.
• Observe the color changes. What do you see? Encourage your scientist to write down what color each substance turns. You can use crayons or markers to help keep track of color changes.

Expand on the Activity:

• What color changes did you see? Did you notice any patterns?

If you use vinegar or lemon juice, what do you think will happen to the color of the DIY pH indicator if you add baking soda or an antacid tablet

• For another hands-on chemistry experiment, try making your own STEM slime activity ! 

The Science: pH and pH indicators

• pH is a measurement of how acidic or basic something is. It is measured on a scale of 0-14.
• A substance with a pH of 7 (like distilled water) is neutral. A substance with a pH of less than 7 is an acid. The closer the number gets to zero, the stronger the acid is. A substance with a pH of more than 7 is a base. The closer the number is to 14, the stronger the base is.
• Strong acids and bases can be very dangerous, while weaker acids and bases (those with a pH close to 7) are safer to use.
• We find acids in many of the foods we eat, as well as in our stomachs. Acids found in foods give them a sour taste.
• Bases are commonly found in cleaning products and antacid medications. Bases feel slippery and are rare in food because they taste bitter. For reference, think about the taste of soap!
• pH indicators are compounds that change color in the presence of an acid or a base.
• Different pH indicators have different ranges. Some may only be able to show whether something is acidic or basic, while others may have a wide range of colors that can show different strengths of acids and bases. Some may be better for showing the pH of acids, while others may be better at showing the pH of bases. In a lab, the best indicator to use depends on the pH range you want to see.

Learn More: Chemistry

• There are several different definitions of acids and bases in chemistry.
• A simple chemical definition of an acid is a substance that releases hydrogen ions (H+) when dissolved in water. A simple chemical definition of a base is a substance that makes hydroxide ions (OH-) when dissolved in water or a substance that takes hydrogen ions from an acid.
• Ions are positively (+) or negatively (-) charged particles of an element.
• Many red, purple, and blue plants contain chemicals called anthocyanins, which are weak acids that dissolve in water and change color in response to changes in pH. Because of this, plants with anthocyanins like red cabbage and blueberries can easily be made into pH indicators.

Did you make and test your own indicator? We’d love to see how it turned out! Snap a photo of you making or experimenting with your indicator and submit it to our Science Showcase here or use #OSCatHome on social media!

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Science Projects > Chemistry Projects > Acid Base Reactions & pH Experiments  

Acid Base Reactions & pH Experiments

Experimenting with acids and bases can make for exciting chemistry projects!

Acidic solutions have a higher concentration of hydrogen ions (H+).

These are hydrogen atoms that have lost an electron and now have just a proton, giving them a positive electrical charge.

Basic solutions, on the other hand, contain hydroxide ions (OH-). One of the simplest activities to show how acids and bases react with each other (and to demonstrate their different properties) is to make a vinegar and baking soda volcano .

For another reaction experiment , put an Alka-Seltzer tablet in the bottom of a clear plastic film canister (the kind where the cap fits inside instead of closing over the outside).

Fill the canister with warm water and then quickly put the cap on and watch the acid-base reaction!

The pH scale is used to measure how acidic or basic a solution is. Acids have a pH below 7; bases have a pH above.

Neutral solutions (like distilled water) with a balanced number of H+ and OH- ions have a pH of 7. Do the following projects to explore the cool effects of pH.

Litmus is a natural acid-base indicator extracted from a type of lichen. If you have red and blue litmus paper , you can test different solutions for whether they are acids or bases.

Blue litmus paper turns red when a solution is acidic; red litmus paper turns blue in basic solutions.

Try testing window cleaner, toilet bowl cleaner, orange juice, and apple juice—pour a little of each into separate test tubes or small glasses or jars.

Use the litmus paper to determine which are acids and which are bases. Here are the pH levels of some other substances that you might test:

• Lemon juice (2)
• Vinegar (3)
• Egg whites (8)
• Baking soda (9)
• Ammonia (10)

Human blood has an ideal pH of 7.4; even slight fluctuations can seriously affect our bodies.

You can also make your own pH indicator —use a blender to mix one part chopped red cabbage with two parts boiling water and use the juice to test different solutions.

Acids will turn the pigments in the indicator to a reddish color; bases will turn the pigments bluish or yellow-green.

Mystery Pitcher

Make ordinary water turn bright pink and then back to clear! This makes a great “magic trick” to impress your friends – just be careful no one mistakes it for fruit punch and drinks any!

>> Check out our project video to see this trick in action!

What You Need:

• Phenolphthalein solution
• Sodium carbonate
• 5 glasses and a non-see-through pitcher of water

What You Do:

1. In the first glass put a little less than 1/8 teaspoon of sodium carbonate, in the second put 6 drops of phenolphthalein solution, and in the third put three droppers-full of vinegar.

2. Add a few drops of water to the first glass and stir to dissolve the sodium carbonate.

3. Fill all the glasses with water from the pitcher, then pour all of them back in the pitcher except for the glass with vinegar.

4. Refill the remaining four glasses – the water will be red!

5. Now pour all five glasses back in the pitcher. Refill the glasses one last time—the liquid will be colorless again!

What Happened:

Phenolphthalein is a pH indicator, but it only turns colors in reaction to bases. When you poured the four glasses back into the pitcher, the phenolphthalein reacted to the sodium carbonate, a base, and turned the solution to bright pink “kool-aid.” To change it back to “water,” all you had to do was add the acidic vinegar, which turned the phenolphthalein colorless again.

Rainbow Reaction Tube

Amaze your friends by mixing two solutions to make a rainbow!

Watch as purple sinks to the bottom and red floats to the top, and they mix together to form every color in between.

• 10ml graduated cylinder
• Universal indicator
• Distilled white vinegar

2. Add 3 drops of vinegar to the solution in the graduated cylinder, and it should turn red.

3. In a beaker, put two scoops of sodium carbonate and then add about 30 ml of water. Mix together with the stirring rod until the sodium carbonate dissolves. The solution should be clear.

4. To start the reaction, fill one dropper full with sodium carbonate solution. Squeeze the dropper into the graduated cylinder quickly, rather than drop by drop. The clear solution should instantly turn dark purple, and slowly sink to the bottom, swirling around to make the rainbow.

5. Let the contents of the cylinder settle, until you can see each color from bluish-purple to red. To make the rainbow disappear, pour it into an empty beaker, and it should turn yellow or yellowish green.

Universal indicator changes colors to show the pH level of a substance. In this case, when you mixed an acidic solution (vinegar) with a basic one (sodium carbonate), the indicator made a colorful spectrum — from dark blue to red. Interestingly, if you had added the solutions in the opposite order, you would not have seen a rainbow. To get the rainbow effect, another scientific principle is at work— density . The sodium carbonate solution you made is denser than the indicator solution, so it sinks to the bottom. As the sodium carbonate solution makes its way to the bottom, some of its molecules mix with vinegar molecules, making a new solution, which shows up as a color of the pH scale.

If you don’t turn the graduated cylinder upside down, the rainbow will last several days. Over time the colors will mix together through the process of diffusion. The molecules of each solution will mix throughout the graduated cylinder, rather than staying concentrated at the top or bottom. Once you mix the acid and base solutions together, the solution will be pH neutral, and look yellow or slightly green.

To make a different kind of rainbow tube, try making this rainbow density column with all household materials.

More Chemistry pH Projects:

• Green Eggs & Ham
• Fizzy Bath Bombs
• Acid & Apples
• Copper-Plated Nails

Welcome! Read other Chemistry articles or explore the rest of the Resource Center, which consists of hundreds of free science articles!

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“Blueberries indicator” experiment

How to make pH indicator from blueberries

You’ve all heard of the in­di­ca­tors phe­nolph­thalein, lit­mus and methyl-or­ange, but un­less you’re a chemist, they’re not easy to ob­tain. But there’s a wor­thy al­ter­na­tive to them – juicy blue­ber­ries! In this ex­per­i­ment you’ll learn how to ex­tract col­or­ing agents from blue­ber­ries, and use them to de­ter­mine the acid­i­ty of so­lu­tions.

Safe­ty pre­cau­tions

Ob­serve safe­ty mea­sures when work­ing with heat­ing de­vices and hot liq­uids.

Reagents and equip­ment:

• blue­ber­ries (200 g);
• hot wa­ter (150 ml);
• 9% ta­ble vine­gar (100 ml);
• lemon juice (100 ml);
• fizzy wa­ter (car­bon­ic acid so­lu­tion, 100 ml);
• wa­ter (100 ml);
• 2% bak­ing soda so­lu­tion (100 ml);
• pipe-clean­ing liq­uid (10% sodi­um hy­drox­ide so­lu­tion, 100 ml);
• 15 glass­es;
• glass con­tain­er;
• cot­ton wool.

Step-by-step in­struc­tions

In a glass con­tain­er, crush blue­ber­ries and pour hot wa­ter over them. Fil­ter the re­sult­ing mix­ture through a fun­nel with cot­ton wool . Us­ing a pipette, drip sev­er­al drops of fil­trate into the glass­es and grad­u­al­ly fill with the fol­low­ing so­lu­tions: lemon juice, acetic acid, fizzy wa­ter , plain wa­ter, bak­ing soda so­lu­tion and pipe-clean­ing liq­uid. Watch the in­di­ca­tor change col­or from red to yel­low through blue.

Pro­cess­es de­scrip­tion

The po­ten­tial of hy­dro­gen (acid­i­ty) of pH is a mea­sure­ment of the ac­tiv­i­ty of hy­dro­gen so­lu­tions in a so­lu­tion. If pH>7, the medi­um is al­ka­line, if pH<7, it is acidic. If pH=7, the medi­um is neu­tral. House­hold clean­ing agents with a strong acidic or al­ka­line pH may be harm­ful to the body. The in­di­ca­tor does not make a sub­stance less dan­ger­ous and does not pro­vide pro­tec­tion from it – it sim­ply warns of dan­ger.

The ”caus­tic­i­ty” of sub­stances can be de­ter­mine in the home us­ing a blue­ber­ry in­di­ca­tor. Blue­ber­ries con­tain col­or­ing agents – an­tho­cyanins . De­pend­ing on the acid­i­ty of al­ka­lin­i­ty of the medi­um, an­tho­cyanins turn dif­fer­ent col­ors. In a strong acidic medi­um (lemon juice, vine­gar) they turn red, in a weak acidic and neu­tral medi­um they turn pur­ple, in a weak al­ka­line medi­um they turn blue, and in a strong al­ka­line medi­um they turn yel­low.

Dozens of experiments you can do at home

One of the most exciting and ambitious home-chemistry educational projects The Royal Society of Chemistry

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Natural Indicators: Meaning, Example, Experiment

Introduction to Acids and Bases:  Certain food items like lemon juice, orange juice, curd and vinegar taste sour. It is so because they contain acids. It means that the chemical nature of these substances is acidic. The word acid is derived from the Latin word  acere , which means sour. The acids in these items are natural acids, i.e. they inherently possess the acidic quality. 

Another domestic example of learning bases and acids is baking soda. If it does not taste sour, then it means that it is not acidic. Baking soda is bitter, and rubbing its mixture between your fingers feels soapy. The bitter taste and soapy feel of these substances makes them bases, and they are considered basic in nature. 

What Is a Natural Indicator?

In cases where every substance cannot be tasted, there should be a method to determine its nature. Certain types of substances are utilised in such instances to determine whether a substance is basic, acidic or neutral. These substances are known as indicators. The indicators change their natural colour based on the nature of the solution they are brought in contact with. The indicators which are found naturally are known as Natural Indicators. Some natural indicators are the litmus test, china rose petals, turmeric etc. A Natural Indicator is a chemical compound that helps us determine whether the nature of a particular substance is acidic or basic, by changing its colour. The most common natural indicator is a litmus, which is extracted from the lichens. It is purplish in colour in distilled water. When it is added to an acidic solution, the colour of the litmus turns red. When it is inserted in a basic solution, it turns blue in colour. Thus, a natural indicator help in determining whether a given solution is acidic or basic.

Natural Indicators Around Us

Turmeric is an excellent natural indicator. Mix some turmeric powder with water and make a paste. Put it on a filter paper to make turmeric paper. Once the paper is dried, you can use it as a litmus paper to test the acidic nature of a substance. This is why a cloth on which turmeric spills turns red when it comes in contact with soap, as soap is acidic.

There are flowers that like hydrangeas, that can find whether the soil is acidic or basic. Such flowers turn blue in colour if the soil is acidic in nature, purple if the soil is neutral in nature and turn pink if the  soil  is basic. Also, the brightness of the color depends on the level of acid or base in the soil. The soil which is very acidic gives dark blue flowers. The soil which is highly basic gives dark pink flowers. Such natural indicators are utilised to determine the  hydrogen  ions (H+) and hydroxyl ions (OH-) present in a solution.

Also, olfactory indicators can change their odour. The most common examples of olfactory indicators are vanilla extract, onion, garlic, etc.

Importance of Natural Indicators

In chemistry, biology, water purification, agricultural practices, nutrition, civil engineering, afforestation, water treatment, oceanography, environmental science, medicine, agronomy, and many other fields, determining acidity or basicity of a substance is crucial. Students can do their litmus test using daily commodities commonly found in our homes. Below is an easy experiment to determine whether red cabbage is a natural indicator:

Natural Indicators Experiment

Aim: To determine a natural indicator using red cabbage. Objective of the experiment: To find out if red cabbage is a natural indicator. Experiment steps: 

• Step 1: Cut some red cabbage and put it in a mixer or a grinder.
• Step 2: Add some water in the jar and grind it until a juicy substance is prepared.
• Step 3: Strain this mixture into a vessel.
• Step 4: Take a few different items like milk, lemon, vinegar, bleach, ammonia, etc and mix them with the red cabbage solution you just created.
• Step 5: The colour of the substance added will change according to its nature of acidity, neutrality or basicity.

Observation of the experiment: The acidic substances change the natural color of the solution from purple to pink or red, depending on the acidity. Substances that are neutral turn the purple solution to blue. Substances which are basic, change the color of the purple solution to green or yellow. Inference of the experiment: From the above experiment, it can be inferred that a red cabbage is a natural indicator.

Conclusion About Acids, Bases and Natural Indicators

From the above information, it can be concluded that:

• Almost all acids are sour in taste. 
• Almost all bases are soapy to touch bitter in taste. 
• Acidic substances turn a blue litmus into red. 
• Basic substances turn a red litmus into blue. 
• Substances that are neither acidic nor basic are neutral in nature. 
• The solutions that determine the nature of substances whether they are acidic, basic and neutral, are known as indicators. 
• When an acid and a base neutralise each other the end result is a salt, which can be acidic, basic or neutral in nature.

We hope this article on Natural Indicators was useful to you. For more such easy & informative reads, keep visiting Embibe .

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• Current Syllabus:
• Static and Dynamic Equilibrium
• Factors That Affect Equilibrium
• Calculating The Equilibrium Constant Keq
• Solution Equilibria
• Properties of Acids and Bases
• Using Brønsted–Lowry Theory
• Quantitative Analysis
• Nomenclature
• Hydrocarbons
• Products of Reactions Involving Hydrocarbons
• Reactions of Organic Acids and Bases
• Analysis of Inorganic Substances
• Analysis of Organic Substances
• Chemical Synthesis and Design
• 1. Fossil Fuel Products
• 2. Biomass Research
• 3. Renewable Ethanol
• 4. Electrochemical Methods
• 5. Nuclear Methods
• 1. Indicators
• 2. Acidic Oxides
• 4. Acid/Base Definitions
• 5. Esterification
• 1. Chemists and Reactions
• 2. Maximising Production
• 3. Manufactured Products
• 4. The Atmosphere
• Industrial Chemistry
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• The Biochemistry of Movement
• The Chemistry of Art
• Forensic Chemistry
• Other Subjects:
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Natural Indicator Experiment

The acidic environment‎  >  ‎ 1. indicators‎ > ‎.

Perform a first-hand investigation to prepare and test a natural indicator

• Select a suitable coloured plant material, such as purple cabbage.
• Boiling it in water.
• Crushing it with water or alcohol using a mortar and pestle.
• Decant the solution from the solid.
• Dip the ends of two strips of filter paper into the indicator and allow to dry.
• Using an eyedropper, apply a drop of strong acid to one strip and a drop of strong base to the other strip.
• Record any changes in colour.
• Add additional drops of acid and base to the strips until no further changes in colour are observed.
• Initial/Neutral colour :  Purple
• Colour when exposed to strong acid :  Pink , then  Red
• Colour when exposed to strong base :  Blue-Green , then  Yellow

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