acids and bases experiment with red cabbage

• 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.

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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!

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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!

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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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Red Cabbage Chemistry

Learn how to make a red cabbage indicator that will test the acidity or alkalinity of certain liquids.

Print this Experiment

Ahh, the sweet smell of science! This next activity is super smelly, but really cool activity. Plug your nose and get ready to make your own red cabbage indicator that will test the acidity or alkalinity of certain liquids. Everyone loves searching for acids and bases in the kitchen, right?

Experiment Videos

Here's What You'll Need

Red cabbage, clear drinking glasses, white paper, apron or lab coat (cabbage juice can leave nasty stains), test chemicals: vinegar, baking soda, lemon juice, washing soda, laundry detergent, soda pop, and alka-seltzer, adult supervision, let's try it.

Peel off three or four big cabbage leaves and put them in a blender filled one-half full with water. Blend the mixture on high until you have purple cabbage juice.

Pour the purplish cabbage liquid through a strainer to filter out all of the big chunks of cabbage. Save the liquid for the experiments to follow.

Set out three glasses, side by side. Fill each glass three-fourths full with cabbage juice.

Add a little vinegar to the first glass of cabbage juice. Stir with a spoon and notice the color change to red, which indicates that vinegar is classified as an acid. All acids will turn red when mixed with cabbage juice.

In the second glass, add a teaspoon of washing soda or laundry detergent. Notice how the liquid turns green, indicating that this chemical is a base.

Keep the two glasses of red (acid) and green (base) liquid for future reference. Fill the third glass of purple cabbage juice to show the color of a neutral solution.

How Does It Work

Some substances are classified as either an acid or a base. Think of acids and bases as opposites—acids have a low pH and bases have a high pH. For reference, water (a neutral) has a pH of 7 on a scale of 0–14. Scientists can tell if a substance is an acid or a base by means of an indicator . An indicator is typically a chemical that changes color if it comes in contact with an acid or a base.

As you can see, the purple cabbage juice turns red when it mixes with something acidic and turns green when it mixes with something basic. Red cabbage juice is considered to be an indicator because it shows us something about the chemical composition of other substances.

What is it about cabbage that causes this to happen? Red cabbage contains a water-soluble pigment called anthocyanin that changes color when it is mixed with an acid or a base. The pigment turns red in acidic environments with a pH less than 7 and the pigment turns bluish-green in alkaline (basic) environments with a pH greater than 7.

Red cabbage is just one of many indicators that are available to scientists. Some indicators start out colorless and turn blue or pink, for example, when they mix with a base. If there is no color change at all, the substance that you are testing is probably neutral, just like water.

Take It Further

You can also make your own pH indicator strips, like you see lifeguards using to test the pH of pool water. To do this, soak some coffee filter paper in concentrated cabbage juice. Remove the paper from the cabbage juice and hang it up by a clothespin to dry. Cut the dried paper into thin strips. Dip the strips into various liquids to test their pH. The redder the strip turns, the more acidic the liquid is. The greener the strip turns, the more basic the liquid is. If it stays purple, you guessed it, the substance you’re testing is probably neutral.

Science Fair Connection

Preforming the Red Cabbage Chemistry experiment is pretty cool, but it isn’t a science fair project. You can create a science fair project by identifying a variable, or something that changes, in this experiment. Let’s take a look at some of the variable options that might work:

• Fill additional glasses with purple cabbage juice. Look around your home. Think of other household chemicals that you use daily (shampoo, glass cleaner, dish soap, hand soap, salt, ammonia, etc.) Try adding a small amount of each household chemical to your cabbage juice. Note the color change to determine if the chemical is an acid (red) or a base (green).
• Fill additional glasses with purple cabbage juice. Look around your kitchen. Think of other household liquids that you use consume (soda, milk, orange juice, coffee, lemonade, etc.) Try adding a small amount of each liquid to your cabbage juice. Note the color change to determine if the chemical is an acid (red) or a base (green).

These are just a couple of ideas, but you aren’t limited to those! Try coming up with different ideas of variables and give them a try. Remember, you can only change one thing at a time. If you are testing a different household chemicals, make sure that the other factors remain the same!

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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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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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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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How to make a red cabbage pH indicator

September 24, 2021 By Emma Vanstone Leave a Comment

Red cabbage indicator is a simple way to tell whether a substance is an acid or alkali .

Acids can be found in the food we eat, in our bodies and around the home. Some acids, especially those found in cleaning products, can be very harmful, so take care when using them and always read their hazard labels.

Alkalis are a group of chemicals that react with acids. Substances such as soap are alkalis and bicarbonate of soda, which we use in baking, and also harmful things like bleach are alkalis.

You can make a straightforward red cabbage pH indicator to determine whether a substance is an acid or alkali. This activity is a great way to introduce the pH scale to kids !

What is a pH indicator?

We use a substance called an indicator to test the pH of something. An indicator will change colour in the presence of an acid or alkali. The pH scale goes from 0 to 14. A substance with a pH of 0 is a strong acid, pH 14 is a strong alkali, and pH 7 is neutral.

You can make an indicator using red cabbage.

What you need to make a red cabbage indicator

• Red cabbage – chopped
• Cups or small containers
• Different substances to test – baking soda, vinegar, lemon juice and lime juice all work well.

Place the chopped cabbage into the pan and cover it with water.

Simmer for 10 minutes.

Sieve the water and cabbage into a jug – you will notice that the cabbage liquid is very purple.

Leave to cool for about 30 minutes.

Add a small amount of each test substance to a separate cup or container, and try to keep the amount of test substance the same.

Use a pipette to drop about 20ml of red cabbage indicator into each cup and record the colour the indicator changes to.

Safety note

Wear safety goggles if using strong acids/bases.

An adult should help with the chopping and heating of the cabbage.

Red Cabbage Indicator pH Colours

Universal Indicator pH colours

Notice that the colours for acids and alkalis are different when using a universal indicator.

When using the red cabbage indicator, the colour of the liquid will change from purple to red if it is an acid and from purple to green if it is an alkali. The different shades of colour will depend on the strength of the acid or alkali. The substance is said to be neutral if there is no colour change.

How does the pH indicator work?

Acids and bases are opposites; acids have a low pH, and bases have a high pH.

Red cabbage contains a pigment called anthocyanin, which is what changes colour.

More Red Cabbage Indicator Experiments

Make colour changing fizzy potions !

Make your pH test strips by soaking filter paper in red cabbage indicator and leaving it to dry. Once dry, cut the filter paper into strips and dip it into test substances. Try testing milk, fizzy drinks or soap. Can you predict their pH before testing?

Try using beetroot juice instead of red cabbage; which works best?

You could also try blowing into the indicator. What happens?

A pH indicator can also be made from red poinsettia leaves !

What happens when you blow into the red cabbage indicator?

The indicator should turn red as the carbon dioxide you breathe out reacts with the water to form carbonic acid.

Last Updated on October 16, 2023 by Emma Vanstone

Safety Notice

Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

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Acid Base Cabbage Juice Science Experiment

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We had so much fun experimenting with a cabbage juice science experiment recently. This is an awesome chemistry experiment for teaching about acids and bases.

Did you know that red cabbage juice contains a natural pH indicator that changes colors according to the acidity of the solution?

Very acidic solutions will turn it a red and orange colors. Neutral solutions result in a greenish color. Basic ( or alkali) solutions appear in blues and purples. So, it is possible to determine the pH of a solution based on the color it turns the red cabbage juice.

How to Do the Acid Base Cabbage Juice Science Experiment:

Supplies needed:.

• Red Cabbage
• Large pot of boiling water
• Litmus paper or coffee filters (to make your own)
• Various substances to test the pH of
• Several cups- can use paper cups, plastic cups or glasses from home

This experiment would be great to use for a science fair project. It is simple to put together and can be done without acquiring too many extra supplies and ingredients.

How to Make Cabbage Juice:

You will need to start by making some red cabbage juice. Start by chopping up a head of red cabbage. We only used half a head for your experiment. You can save the other half for your dinner salads!

Put the red cabbage into a large pot & add water to cover. Boil until soft & the water is deep purple. Let it cool.

Remove the cabbage, but save the water!  You can use the cooked cabbage in a yummy soup!

The easiest way to do this is to drain the water from the cabbage into another bowl with a strainer.

Pour the cooled cabbage water into small cups. Collect some household items that could create reactions (acid, base, neutral).

Cabbage Juice Litmus Test ~ Acids or Bases?

Now you are going to collect a variety of household substances to see if they are an acid, a base or a neutral.

Some ideas of things to test:

• lemon juice
• baking soda
• window cleaner
• hand sanitizer
• cola/something carbonated
• antacid tablets
• rubbing alcohol
• cream of tartar
• tomato sauce

Add a little bit of each substance into your cups of cabbage water- label the cups so you remember what you put into each one.

The Science Behind the Cabbage Juice Chemistry Experiment:

Cabbage juice is an acid-base indicator (a chemical that tells you something about other chemicals). If it turns a pinkish color, the substance was an acid. If it turns a greenish color it base.   If it stays about the same, it is neutral. Also acids and bases can react to one another turning neutral.  There is a whole color scale you can use to determine the exact levels!

Litmus Test:

Instead of pouring the substances into the cabbage water, you can also test the acidity by dipping litmus paper into the substance.

However, you can also tell if it is an acid or base by the color it turns the cabbage juice as I showed you above.

 This was a simple & fun experiment! The kids loved guessing what would happen with each thing they poured into the cabbage water.

How to Make Your Own Litmus Paper:

Don’t want to buy the litmus paper? Or can’t find any?

You can make your own litmus testing paper from the cabbage water, too! It’s really quite easy. This will just make the experiment take a bit longer with the dry time.

This can be done with coffee filters or with paper towels. Cut them into small even strips.

Use the boiled cabbage water and dip the strips of coffee filters or of paper towels into the water. Lay them on a tray or a cooling rack with a tray underneath. Let them dry completely.

Use them the same way the litmus paper strips are used.

Do some more cabbage juice science and check out how we made  Green Eggs with Cabbage Juice !!

Former school teacher turned homeschool mom of 4 kids. Loves creating awesome hands-on creative learning ideas to make learning engaging and memorable for all kids!

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What a fun experiment! We dabbled in chemistry experiments at the beginning of the year with another family (then the other mommy had a baby). This would be a great experiment for us to try – to get us back into the swing of things. Thanks for posting! =)

How cool! We did this last year in CC, but not with cabbage. I’ll have to try this with the kids. Thanks for sharing!

Very cool. I did not know that about cabbage. My kids will love this. Thanks for sharing at Mom’s Library!

What a great experiment! Thank you for sharing this in Homeschooling on the Cheap! You are one of my featured post. Stop in and see your feature and share more of your wonderful ideas!

Have a great week, Kelli http://3boysandadog.com/deals/2012/homeschooling-on-the-cheap-october-18-2012/

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Simple and Colorful Science with Acids, Bases, and Red Cabbage

Ingredients for Red Cabbage Indicator

• 2 cups red cabbage leaves
• 2 cups hot water

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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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Determining Acids and Bases: Red Cabbage Lab Experiment