How to Dye Eggs Naturally Using Acid/Base Chemistry

One of the things I anticipate most about this season is dying eggs with my family. It's one of those things that is always fun no matter how old you get. This year we added another fun dimension to our egg-dying party by incorporating acid/base chemistry into it. For those of you who love science AND love doing things naturally (even organically!), this is the perfect activity for you.

The star of this show is red cabbage. It contains a chemical called anthocyanin that changes color depending on the acidity of its environment. This means it is a pH-indicator, a gauge that tells you how acidic or basic the surrounding environment is. Red cabbage is purple in a pH-neutral environment, but it turns pink in an acidic environment and bluish-green in a basic environment. We recently did another experiment with red cabbage where we froze cabbage-water into ice cubes and tested the acidity of different solutions. It's the same chemistry, just a different way to see it.

Total Time: This experiment takes awhile, though you don't have to actively be doing anything for most of the time. Allow about 40 minutes to boil the eggs and cabbage and at least 12-18 hours for the eggs to sit in the fridge in the cabbage solution. Painting the eggs only takes 10-20 minutes at the end.
Safety Concerns: As always, be careful when boiling things with kids around. Use caution when cooking and handling the hot eggs and cabbage.

Materials You Need:
One half of a head of red cabbage
One dozen large eggs
Slotted spoon
Lemon juice or vinegar
Baking soda
Q-tips or paint brushes to paint the eggs

Directions:
To prepare the eggs:

1. Place eggs in a large pot in a single layer.
2. Chop up your cabbage into small pieces and throw them into the pot with the eggs. Add enough cold water to cover everything by one inch.
3. Bring the cabbage/eggs/water mixture to a boil. Remove from burner and cover the pot.
4. Let your mixture stand for about 12 minutes for large eggs (9 minutes for medium eggs, 15 minutes for extra large eggs).
5. Using a slotted spoon, remove your eggs from the pot and cool completely under cold running water or in a bowl of ice water. They will most likely still be very white at this point.
6. Refrigerate your eggs. Once your cabbage water has cooled to room temperature, place your eggs back into the pot and refrigerate everything together. Make sure the eggs are completely submerged in the water for best color.
7. Leave your mixture in the refrigerator overnight.

 To paint your eggs:

1. Use a spoon to scoop your eggs out of the cabbage mixture. Feel free to rinse them off and pat them dry. They should be some shade of bluish-purple (depending on how acidic your tap water is!).
2. Pour some lemon juice or vinegar into a small cup (this is your acid).
3. In another cup mix 1/2 tsp baking soda with enough water to dissolve it (this is your base).
4. Using your Q-tips or paint brushes, paint your eggs! Watch as your eggs change from blue to pink when you paint with lemon juice and from blue to greenish-blue when you paint with your baking soda solution (this may not show up well until the eggs are dry again).
5. Feel free to try painting your eggs with other solutions from around the house to see what happens. Some ideas to try are washing soda, cream of tartar, and antacids. If your egg turns pink you know the solution is acidic, if it turns green you know it's basic!

Something interesting that I noted was that the cabbage solution turned out very blue this time, whereas last time we did this experiment it was beet red. We moved to a different county since last time, so does that mean our drinking water is more basic on this end of the city? Or is it a difference in the cabbage I purchased each time? I don't know, but I think it's definitely worth finding out!

Print These Instructions

You can see the whitish-pink spots where we painted with lemon juice. On the right of the egg you can see it's a little bit green, which is where we painted with baking soda.

Thanks to the Kitchen Pantry Scientist for this awesome idea!

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Make Your Own pH Indicator Using Red Cabbage

 Who here likes red cabbage? Anyone? Anyone? For those of you who may not like to eat it, I've found a great new way to use it in a science experiment! Anything for the kiddos, right?

It turns out that red cabbage contains a chemical called anthocyanin that changes color depending on the acidity of its environment. In an acidic environment it is reddish-pink, in a neutral environment it is purple, and in a basic (or alkaline) environment it turns bluish-green and even yellow. This is a great way to introduce the concept of acids and bases to a child since they can see the color change before their very eyes.

This experiment can be found in 50 Science Things to Make & Do. We use this book all the time up in here.

Let's get started, shall we?

Total Time: 40 minutes to prepare the indicator, two hours to let it freeze; 10 minutes to carry out the rest of the experiment
Difficulty: This one definitely requires the aid of an adult to prepare the indicator, unless you trust your child with a sharp knife and a hot saucepan full of boiling cabbage (I don't, personally). It's pretty easy, though, as far as actual skill goes.

Materials You Need:
One half of a head of red cabbage
Ice cube tray
Tall clear cups
Vinegar
Baking Soda
Water
Optional: More acidic/basic household items such as lemon juice, washing soda, cream of tartar, or antacids

Directions:
To make the indicator solution:

1. Chop up your red cabbage into small pieces. Place 2-3 cups in a saucepan and cover with water.
2. Bring the solution to a boil and then turn off the heat. Let it sit for about 30 minutes to cool down.
3. Pour the cabbage water through a strainer into a jar or large measuring cup. The dark purple liquid in the jar is your indicator. Make soup with the leftover cabbage pieces.
4. Pour your red cabbage indicator liquid into the compartments of an ice cube tray. Freeze for a couple of hours to make ice cubes. (Don't eat these. They taste like cabbage water.)

pH Experiment:

1. Fill one cup with water, one with vinegar, and one with a teaspoon of baking soda mixed with water.
2. Drop a couple of indicator ice cubes into each cup. Notice how the colors change in each one. Draw a picture of what you see.
3. Repeat with other acidic or basic household items in other cups.

Print These Instructions
 
Now, I'll be honest. My son wasn't all that impressed with this experiment. He may just be too young to grasp the idea of what acids and bases are. The idea that we could make our very own pH indicator was kind of ho-hum for him, even though I thought it was pretty cool. I was shocked at how fast the colors changed and how delightfully brilliant and beautiful the colors were. This experiment worked perfectly, but I think it will be more impressive for a child closer to 8 or 9 years old than it was for my four-year-old. Let me know how it works and how your kiddo enjoyed it!

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