red cabbage experiment introduction

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Red Cabbage Science Experiment

I’m not a big fan of cabbage except for when it’s used for science! Food science is super cool and is awesome for kids. This isn’t the sweetest-smelling science experiment we have done, but once you get past the smell this cabbage science experiment is fascinating chemistry . Find out how to test pH with red cabbage!

Red Cabbage Experiment

Let’s make an indicator and test it out on common household solutions!

Watch the video:

Grab a head or two of red cabbage and let’s get started! Even if your kids swear they hate cabbage, they will be loving it (at least for science sake) after this awesome cabbage chemistry experiment.

• Red cabbage
• Several jars or small containers
• Lemons (grab a few for a couple of extra science activities you will find below)
• Baking soda
• Other acids and bases to test (see more items to test below)
• pH test strips (optional but older kids will enjoy the added activity)

Instructions:

STEP 1. S tart by cutting the red cabbage roughly into small pieces.

The cabbage indicator can be prepped ahead of time but I love when you can involve kids in the whole process!

STEP 3. Place your cut up cabbage in a medium saucepan and boil for 5 minutes.

STEP 3. After the 5 minutes, cover and let it rest for 30 minutes.

STEP 4. Go ahead and carefully pour the liquid into the jars. This is your acid-base indicator! ( You can dilute the cabbage juice and it will still work )

Testing Solutions With Red Cabbage Indicator

Now it’s time to test the pH of different items. We have a few common acids and bases for you to start with. This experiment is set up so that you add some of the acid or base to the jar of red cabbage juice, and observe the color change.

Please take care when mixing different items into your cabbage pH indicator. Adult supervision is recommended at all times. This NOT an edible science experiment!

You can find even more solutions to test out! Depending on your kid’s interest levels and needs, you could turn this into a huge science experiment. This red cabbage experiment also makes a terrific science fair project !

Before your kids start testing each one, have them make predictions about what color change they will see. Remember, red color is acidic and green color is basic.

Here are a few acids and bases to test…

1. LEMON JUICE

Squeeze lemon juice into one of the jars. What color did it change to?

What else can you do with lemons? We have a couple of fun ideas for exploring fun chemistry with this fruit!

• Erupting Lemon Volcano
• Make Fizzing Lemonade

2. BAKING SODA

Put a teaspoon of baking soda into a cabbage juice jar. Notice what happens! What color did the indicator change to?

If you have ever experimented with baking soda and vinegar, your kids may already know that baking soda is a base and vinegar is an acid. Vinegar is also a great liquid to use to test with your red cabbage indicator!

EXPERIMENT WITH: Baking Soda and Vinegar Science

4. BLACK COFFEE

Coffee is a common drink for many people. But is it an acid or a base?

DIY: Make your own pH strips by soaking coffee filters in the cabbage juice and hang to dry, cut in strips!

What Is An Indicator In Chemistry?

pH stands for power of hydrogen . The pH scale is a way to measure the strength of an acid or base solution, and is numbered from 0 to 14.

Distilled water has a pH of 7, and is considered a neutral solution. Acids have a pH lower than 7 and bases have a higher pH higher than 7.

If you ask the kids about what types of things around the house are acidic, they might say vinegar or lemons. An acid is usually recognized as something with a sour or sharp taste.  Baking soda is an example of a base.

An indicator is one way to work out the pH of a solution. Good indicators give a visible sign, usually a color change, when they come into contact with acids or bases. Like our red cabbage indicator below.

Why can red cabbage be used as an indicator to test pH?

Red cabbage contains  anthocyanin, which is a water-soluble pigment. This pigment changes color when mixed with an acid or a base. Redder when mixed with an acid and greener when mixed with a base.

TIP: Here’s a simple pH scale for kids with a little extra information. Plus it gives you a few more items to test once you have made your red cabbage pH indicator!

Click here to get your printable science experiment worksheets!

Applying The Scientific Method

This cabbage PH science experiment is a fantastic opportunity to use the scientific method and start a journal using the free mini pack above. You can read about incorporating the scientific method here , including more information on independent and dependent variables .

The first step in the scientific method is asking a question and developing a hypothesis. What do you think will happen if_______________? I think the_________ will___________if___________. This is the first step to diving deeper into science with kiddos and making connections!

You can also easily turn your cabbage science experiment into a fantastic presentation along with your hypothesis. Check out the resources below to get started.

• Easy Science Fair Projects
• Science Project Tips From A Teacher
• Science Fair Board Ideas

More Fun With Acids and Bases

Simple chemistry is cool! Check out more than 65 chemistry experiments for kids for more ideas!

Printable Science Projects For Kids

If you’re looking to grab all of our printable science projects in one convenient place plus exclusive worksheets and bonuses like a STEAM Project pack, our Science Project Pack is what you need! Over 300+ Pages!

• 90+ classic science activities  with journal pages, supply lists, set up and process, and science information.  NEW! Activity-specific observation pages!
• Best science practices posters  and our original science method process folders for extra alternatives!
• Be a Collector activities pack  introduces kids to the world of making collections through the eyes of a scientist. What will they collect first?
• Know the Words Science vocabulary pack  includes flashcards, crosswords, and word searches that illuminate keywords in the experiments!
• My science journal writing prompts  explore what it means to be a scientist!!
• Bonus STEAM Project Pack:  Art meets science with doable projects!
• Bonus Quick Grab Packs for Biology, Earth Science, Chemistry, and Physics

This is an awesome experiment to do, even for older kids! It shows them that chemistry is very much a part of our lives and are closer to us than we think! I’m sure kids would love it 🙂

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How to Make a Red Cabbage pH Indicator

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Red cabbage indicators that test pH levels are easy to make, exhibit a wide range of colors, and can be used to make pH paper strips. Why? Red cabbage juice contains a natural pH indicator that changes colors according to the acidity of the solution.

Red Cabbage Indicator Basics

Red cabbage contains a pigment molecule called flavin (an anthocyanin). This water-soluble pigment is also found in apple skins, plums, poppies, cornflowers, and grapes. Very acidic solutions will turn anthocyanin into a red color. Neutral solutions result in a purplish color. Basic solutions appear in greenish-yellow. Therefore, you can determine the pH of a solution based on the color that it turns the anthocyanin pigments in red cabbage juice.

The color of the juice changes in response to changes in its hydrogen ion concentration; pH is the -log[H+]. Acids will donate hydrogen ions in an aqueous solution and have a low pH (pH 7).

Materials You Will Need

• Red cabbage
• Blender or knife
• Boiling water
• Filter paper (coffee filters work well)
• One large glass beaker or another glass container
• Six 250 mL beakers or other small glass containers
• Household ammonia (NH 3 )
• Baking soda (sodium bicarbonate, NaHCO 3 )
• Washing soda (sodium carbonate, Na 2 CO 3 )
• Lemon juice (citric acid, C 6 H 8 O 7 )
• Vinegar ( acetic acid , CH 3 COOH)
• Cream of tartar (potassium bitartrate, KHC 4 H 4 O 6 )
• Antacids (calcium carbonate, calcium hydroxide, magnesium hydroxide)
• Seltzer water (carbonic acid, H 2 CO 3 )
• Muriatic acid or masonry's cleaner (hydrochloric acid, HCl)
• Lye (potassium hydroxide, KOH or sodium hydroxide , NaOH)

Procedure for Making Red Cabbage Indicator

• Chop the cabbage into small pieces until you have about 2 cups of chopped cabbage. Place the cabbage in a large beaker or other glass container and add boiling water to cover the cabbage. Allow at least 10 minutes for the color to leach out of the cabbage. Alternatively, you can place about 2 cups of cabbage in a blender, cover it with boiling water, and blend it.
• Filter out the plant material to obtain a red-purple-bluish colored liquid. This liquid is at about pH 7. The exact color you get depends on the pH of the water.
• Pour about 50–100 mL of your red cabbage indicator into each 250 mL beaker.
• Add various household solutions to your red cabbage indicator until it changes color. Use separate containers for each household solution—you don't want to mix chemicals that don't go well together.

Red Cabbage pH Indicator Colors

Tips and safety.

This red cabbage indicator demo uses acids and bases, so use safety goggles and gloves, particularly when handling strong acids (HCl) and strong bases (NaOH or KOH). Chemicals used in this demo may be safely washed down the drain with water.

You can conduct a neutralization experiment using a red cabbage juice indicator. First, add an acidic solution such as vinegar or lemon, then juice until a reddish color is obtained. Add baking soda or antacids to return the pH to a neutral 7.

You can make pH paper strips with your red cabbage indicator. Take filter paper (or coffee filter) and soak it in a concentrated red cabbage juice solution. After a few hours, remove the paper and allow it to dry (hang it by a clothespin or string). Cut the filter into strips and use them to test the pH of various solutions. To test a sample, place a drop of liquid on the test strip. Don't dip the strip in the liquid because you'll get cabbage juice in it. An example of a basic solution is laundry soap. Examples of common acids include lemon juice and vinegar.

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January 26, 2012

Cabbage Chemistry--Finding Acids and Bases

A colorful chemistry challenge from Science Buddies

By Science Buddies

Key concepts Chemistry Acids Bases Light

Introduction You might have done experiments with well-labeled acids and bases in school, but have you ever wondered whether a certain food or chemical around the house is an acid or a base? You can find out using a red cabbage to make an indicator solution.

When two or more ingredients are entirely dissolved in one another, you have a solution. For example, mixing salt with water creates a clear solution, even though the salt is there and the solution tastes salty. When mixed with water, whether a chemical "donates" a charged particle (called an ion) to the solution—in this case, a hydrogen ion—or "accepts" one from it determines whether it's an acidic or basic solution. An indicator changes color when exposed to such a mixture, depending on whether the solution is acidic or basic.

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Background Acids are solutions that lose hydrogen ions and usually taste sour. Some very common household solutions are acids, such as citrus fruit juices and household vinegar. Bases are solutions that pull hydrogen ions out of solution and onto themselves, "accepting" them, and usually feel slippery. Bases have many practical uses. For example, "antacids" like TUMS are used to reduce the acidity in your stomach. Other bases make useful household cleaning products.

To tell if something is an acid or a base, you can use a chemical called an indicator. An indicator changes color when it encounters an acid or base. There are many different types of indicators, some that are liquids and others that are concentrated on little strips of "litmus" paper. Indicators can be extracted from many different sources, including the pigment of many plants. For example, red cabbages contain an indicator pigment molecule called flavin, which is a type of molecule called an anthocyanin. Very acidic solutions will turn an anthocyanin red whereas neutral solutions will make it purplish and basic solutions will turn it greenish-yellow. Consequently, the color an anthocyanin solution turns can be used to determine a solution's pH—a measure of how basic or acidic a solution is.

Materials •    A small red cabbage •    Pot of boiling water •    Strainer •    Two large bowls or pots •    Grater •    Tablespoon measurer •    Large spoon (optional) •    Three or more small, white paper cups (small, white paper drinking glasses or dishes will also work) •    Goggles or other protective eyewear •    Lemon or lime juice •    Vinegar •    Bleach-based cleaning product •    Other foods to test, such as clear soda pop, baking soda solution, egg whites, tomatoes, cottage cheese (optional) Preparation •    Grate a small red cabbage. If you do not want to grate the entire cabbage, grating half of a cabbage should be enough. Put the fine, pulpy grated cabbage into a large bowl or pot. •    Boil a pot of water. Use caution when handling the boiling water. Pour the boiling water into the bowl with the cabbage pulp until the water just covers the cabbage. •    Leave the cabbage mixture steeping, stirring occasionally, until the liquid is room temperature. This should take at least half an hour. The liquid will become red or purplish-red in color. •    Place a strainer over another large bowl or pot and pour the cabbage mixture through the strainer to remove the cabbage pulp. Press down on the pulp in the strainer, such as by using a large spoon, to squeeze more liquid out of the pulp. •    In the bowl, you should now have only liquid that will either be purple or blue in color. This will be your indicator solution, which you will use to test the pH of different liquids. •    Children should wear goggles or other protective eyewear and adults should supervise and use caution when handling bleach and vinegar, because they can irritate eyes and skin. Procedure •    Fill a small, white paper cup, drinking glass or white dish with one tablespoon of your cabbage-indicator solution. What is the color of your indicator solution? •    Add drops of lemon or lime juice to the indicator solution until you see the solution change in color. Gently swirl the solution and make sure the color stays the same. What color did the solution become? •    The color of the solution will change depending on its pH: Red color indicates the pH is 2; Purple indicates pH 4; Violet indicates pH 6; Blue indicates pH 8; Blue-green indicates pH 10; Greenish-yellow indicates pH 12. •     Based on its color, what is the pH of the lemon or lime juice solution? •    In another small, white paper cup, add one tablespoon of your original cabbage-indicator solution. Add drops of vinegar until you see the solution change color. What color did the vinegar solution become? What is the pH of the solution? •    In a third small, white paper cup, add one tablespoon of your original cabbage-indicator solution. Handling it with caution, add drops of the bleach cleaning product until you see the solution change color. What color did the bleach solution become, and what does this indicate about its pH? •    If you want to test the pH of other foods, again add one tablespoon of your original cabbage-indicator solution to a small, white paper cup and add drops of the food until you see the solution change color. If the food is not in liquid form, crush it or dissolve it in a small amount of water before adding it to the indicator solution. What color did the solution become, and what does this indicate about its pH? •     Extra: There are other vegetables and fruits that can be used to make pH indicators as well: red onion, apple skins, blueberries, grape skins and plums. Which different sources of pigment produce the best indicators? •     Extra: You can use an indicator solution to write secret messages. Just use full-strength lemon juice to write an invisible message on paper and let the message dry. To reveal the message, paint cabbage-indicator over the paper with a paintbrush. Observations and results Did the indicator solution change color when you added the lime or lemon juice, vinegar and bleach? Did the solution color indicate that the lime or lemon juice and vinegar were acidic (had a lower pH) and that the bleach was basic (with a higher pH)?

A solution with a pH between 5 and 7 is neutral, 8 or higher is a base, and 4 or lower is an acid. Lime juice, lemon juice and vinegar are acids, so they should have turned the indicator solution red or purple color. Bleach is a strong base, therefore it should have turned the indicator solution a greenish-yellow color.

How basic or acidic a solution is depends on the amount of hydrogen ions in it. A basic solution accepts hydrogen ions (or donates electron pairs as hydroxide ions) whereas an acidic solution donates hydrogen ions (or accepts electron pairs). An indicator, like anthocyanin, responds to the levels of hydrogen ions in the solution. Anthocyanin and other biological pigments absorb certain wavelengths of light and reflect others, and it is the reflected light we see that makes them appear a certain color. Depending on the levels of hydrogen ions in the solution, the indicator pigment undergoes a chemical reaction that changes its chemical structure, making it reflect a different wavelength of light and thereby change color.

Cleanup Dilute the bleach solution with water before pouring it down a drain. (Remember to keep your goggles on when you do this.)

More to explore "Experiments with Acids and Bases" from Fun Science Gallery "Acids and Bases Are Everywhere" from Rader's Chem4Kids.com "Acids, Bases, and the pH Scale" from Science Buddies "Cabbage Chemistry" from Science Buddies This activity brought to you in partnership with Science Buddies

• Acids, Bases and Salts
• Red Cabbage Indicator

Red cabbage Indicator

Red cabbage indicator is a purple-coloured solution that is used to test whether substances are acid or base . Red cabbage that is often found in homes can be used to prepare a solution that acts as a pH indicator. The cabbage basically contains a pigment molecule called flavin or anthocyanin that changes colour depending on the acidity of the solution.

Normally, the purple solution turns red in colour when it combines with something acidic and it turns bluishg-green in colour when it combines with a base. If the substance does not cause the colour to change then it is mostly neutral.

Red Cabbage Indicator pH Colours

Below are the different pH levels and the colours that are obtained during the red cabbage indicator test.

Let us conduct an experiment and observe the results.

To determine which chemicals are bases and which are acids.

Apparatus Required

• Red cabbage leaves
• Lemon juice
• Soda(baking soda)
• Glass jars of a similar size
• Cut the cabbage leaves into small pieces.
• Boil separate cups of water as they will be required to submerge your pieces later on.
• Place the cabbage pieces into a bowl and pour the water in the bowl. Keep it for several minutes so that the cabbage pieces get soaked. You can also use a mixer to grind the leaves and obtain a solution.
• If you are not using the mixture then separate the juice from the leaves.
• Take glass jars and place them about two inches apart. Pour every chemical (lemon juice, vinegar, detergent and soda) into each jar.
• Now to determine whether the substance is a base or an acid pour the cabbage juice into each jar. Here, if the mixture turns pink or red the chemical is an acid and if it turns bluish-green the chemical is usually a base.

This experiment can easily be conducted even in the house and can be used to test different substances which are easily available.

Safety Tips

•  Since the chemical indicator is used to test acids and bases it is always advised to use safety goggles and gloves especially while dealing with strong or concentrated chemicals.
• Chemicals can be washed down the drain safely with water.
• A neutralisation experiment can also be done along with the test.

Making pH Paper

In addition to the solution, pH paper strips can also be created using red cabbage using the steps given below: 1. Firstly, use a filter paper (or coffee filter) and dip it in the concentrated solution obtained from red cabbage.

2. Soak it for some time and later take the paper and dry it.

3. Once it is dried, cut the paper into small strips and they are ready to be used for testing the pH of different solutions.

4. Pour a drop of liquid on the test strip and see what colour is obtained. The strip also turns either red or green depending on whether it is acidic or basic.

Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin!

Select the correct answer and click on the “Finish” button Check your score and answers at the end of the quiz

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