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
Lemon juice or vinegar
Q-tips or paint brushes to paint the eggs
To prepare the eggs:
- Place eggs in a large pot in a single layer.
- 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.
- Bring the cabbage/eggs/water mixture to a boil. Remove from burner and cover the pot.
- Let your mixture stand for about 12 minutes for large eggs (9 minutes for medium eggs, 15 minutes for extra large eggs).
- 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.
- 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.
- Leave your mixture in the refrigerator overnight.
To paint your eggs:
- 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!).
- Pour some lemon juice or vinegar into a small cup (this is your acid).
- In another cup mix 1/2 tsp baking soda with enough water to dissolve it (this is your base).
- 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).
- 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!
|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!