From surface tension to evaporation, science come into play every time you blow a bubble. Here’s some bubble science, along with a recipe for making giant bubbles from my book Outdoor Science Lab for Kids!
Water molecules like to stick to each other , and scientists call this sticky, elastic tendency “surface tension.” Soap molecules, have a hydrophobic (water-hating) end and (hydrophilic) a water-loving end and can lower the surface tension of water. When you blow a bubble, you create a thin film of water molecules sandwiched between two layers of soap molecules, with their water-loving ends pointing toward the water, and their water-hating ends pointing out into the air.
As you might guess, the air pressure inside the elastic soapy sandwich layers of a bubble is slightly higher than the air pressure outside the bubble. Bubbles strive to be round, since the forces of surface tension rearrange their molecular structure to make them have the least amount of surface area possible, and of all three dimensional shapes, a sphere has the lowest surface area. Other forces, like your moving breath or a breeze can affect the shape of bubbles as well.
The thickness of the water/soap molecule is always changing slightly as the water layer evaporates, and light is hitting the soap layers from many angles, causing light waves to bounce around and interfere with each other, giving the bubble a multitude of colors.
Try making these giant bubbles at home this summer! They’re a blast! (It works best a day when it’s not too windy, and bubbles love humid days!)
To make your own giant bubble wand, you’ll need:
-Around 54 inches of cotton kitchen twine
-two sticks 1-3 feet long
-a metal washer
1. Tie string to the end of one stick.
2. Put a washer on the string and tie it to the end of the other stick so the washer is hanging in-between on around 36 inches of string. (See photo.) Tie remaining 18 inches of string to the end of the first stick. See photo!
For the bubbles:
-6 cups distilled or purified water
-1/2 cup cornstarch
-1 Tbs. baking powder
-1 Tbs. glycerine (Optional. Available at most pharmacies.)
-1/2 cup blue Dawn. The type of detergent can literally make or break your giant bubbles. Dawn Ultra (not concentrated) or Dawn Pro are highly recommended. We used Dawn Ultra, which is available at Target.
1. Mix water and cornstarch. Add remaining ingredients and mix well without whipping up tiny bubbles. Use immediately, or stir again and use after an hour or so.
2. With the two sticks parallel and together, dip bubble wand into mixture, immersing all the string completely.
3. Pull the string up out of the bubble mix and pull them apart slowly so that you form a string triangle with bubble in the middle.
4. Move the wands or blow bubbles with your breath. You can “close” the bubbles by moving the sticks together to close the gap between strings.
What else could you try?
-Make another wand with longer or shorter string. How does it affect your bubbles?
-Try different recipes to see if you can improve the bubbles. Do other dish soaps work as well?
-Can you add scent to the bubbles, like vanilla or peppermint, or will it interfere with the surface tension?
-Can you figure out how to make a bubble inside another bubble?
It’s fun to create colorful, swirling marbled designs on eggs, and there’s science behind the fun! Here’s a brief description of each. Click on the blue titles for more instructions and science explanations.
Olive Oil Marbling: You’ll need hard boiled eggs, olive oil, vinegar, and food coloring. We used green, yellow and brown food coloring to make robin’s egg colors.
Natural Dyes: Experiment with fruit, coffee, tea, spices, veggies and even onion skins to create beautiful, natural egg dyes.
Nail Polish Marbling: This one is obviously inedible, but it’s a fun craft project! You’ll need eggs with the yolks and whites blown out, a container that can be thrown away, nail polish in two or more colors, and water. (Project from STEAM Lab for Kids-Quarry Books)
The science behind the marbling fun: Egg dyes and food coloring require an acidic environment to form bonds. That’s why you add vinegar (also called acetic acid) to water and dye when coloring eggs. Things that are less dense than water, like olive oil and nail polish, float on top of water, allowing you to create designs that can be transferred onto your eggs.
Crying over broken candy canes? Cry no more. Make art!
This project is from “Amazing (Mostly) Edible Science,” by Andrew Schloss. For a cookbook full of delicious recipes and the Science-Behind-the-Fun, buy my book Kitchen Science Lab for Kids: Edible Edition here!
*Melted candy can get dangerously hot, so parental supervision is required!
-candy canes (broken or whole), wrappers removed
-heavy-duty aluminum foil
-a cookie sheet
-a wire cooling rack
What to do:
- Preheat oven to 250F.
- Cover cookie sheet with foil
- Place candy canes on foil, not touching each other
- Bake candy canes for around 10 minutes and have an adult check them. They should be stretchy, but not too hot to touch.
- When the candy canes are ready, bend, fold, twist and pull them into cool shapes. Try pulling one long and wrapping it around a chopstick to make a spiral. What else could you try?
- If the candy gets to brittle to work with, put it back in the oven for a few minutes to make it soft again.
The science behind the fun:
If you looks at the ingredients of candy canes, they’re usually made of table sugar (sucrose), corn syrup, flavoring, and food coloring. Glucose and fructose are sweet-tasting molecules that stick together to make up most of the sugars we eat, like table sugar (sucrose) and corn syrup. You can think of them as the building blocks of candy.
At room temperature, candy canes are hard and brittle, but adding heat changes the way the molecules behave. Both table sugar and corn syrup contain linked molecules of glucose and fructose, but corn syrup has much more fructose than glucose, and the fructose interferes with sugar crystal formation. According to Andrew Schloss, “the corn syrup has more fructose, which means the sugar crystals in the candy don’t fit tightly together. The crystals have space between them, which allows them to bend and move without cracking.”
Here’s a great article on the science of candy-making.
If you’re looking for holiday gifts for a science-loving kid, my books Chemistry Lab for Kids, Kitchen Science Lab for Kids and Outdoor Science Lab for Kids include over 100 fun family-friendly experiments! They’re available wherever books are sold.
Here’s some fun footage of kids doing projects from Kitchen Science Lab for Kids. I miss those mask-less photo shoots! (Book Photos by Amber Procaccini and illustrations by @kellyannedalton.) If you’ve got a young scientist on your list, “CHEMISTRY FOR KIDS -Homemade Science Experiments and Activities Inspired by Awesome Chemists, Past and Present” is available everywhere books are sold!
(Adapted from Kitchen Science Lab for Kids)
Grab an extra bag of cranberries this Thankgiving! Kids can use it to reveal invisible messages they write with baking soda and water.
-around 2 cups of cranberries
-small paintbrush, Q-tip, or lollipop stick
Safety tips and Hints:
Boiling the berries should be done by an adult. Keep the lid on the pan, since the air pockets that make cranberries float can also make them explode. Kids can take over once the juice is cool.
When playing with cranberry juice, aprons or old clothes are a good idea, since it stains!
Step 1. Cut a cranberry in half and observe the air pockets that make it float.
Step 2. Boil the cranberries in about three cups of water for 15 to 20 minutes, covered. Listen for popping sounds as the air in the cranberries heats up and they explode.
Step 3. Crush the cooked berries and push the liquid through a sieve or colander to collect the concentrated cranberry juice.
Step 4. Allow the juice to cool and pour it into a casserole dish or cake pan big enough to hold a piece of paper. If your cranberry juice seems thick and syrupy, add a little water, so that it’s thin enough to soak into paper!
Step 5. Test the paper you want to use by cutting a small piece and soaking it in the cranberry juice. If it stays pink, it will work, but if it turns blue or gray, try some other paper.
Step 6. Add a few teaspoons of baking soda to 1/3 cup of warm water and stir well. Don’t worry if you can still see some baking soda.
Step 7. Using a Q-tip, paintbrush, or a homemade writing tool, use the baking soda solution as ink to write a message on your paper. It may take a little practice, so don’t get frustrated.
Step 8. Let your message air dry, or speed things up with a blow dryer.
Step 9. To reveal your message, place your paper in the cranberry juice and see what happens!
*What other natural acid/base indicators could you use to do this experiment? What else could you use as ink.
The Science Behind the Fun:
Cranberries contain pigments called anthocyanins (an-tho-SY-a-nins,) which give them their bright color. In nature, these pigments attract birds and other animals to fruit. This is important because animals eat the berries and spread plants seeds from one place to another.
These pigments, called flavanoids, change color when they come in contact with acids and bases. Cranberry juice is very acidic, and the pigment is pink in acids, but when you add it to a base, it turns purple or blue.
Baking soda is a base, so your baking soda message will turn blue when it comes into contact with the pigments in the cranberry juice. Eventually, when enough cranberry juice soaks into the paper, it will dilute the baking soda, turning the pigment back to red and your message will disappear!
There are over 300 kinds of anthocyanins which are found in many fruits and vegetables including blueberries, red cabbage, grapes and blueberries. Scientists believe they may have many health benefits.
Make mini “lava lamps” from water, baking soda and oil to test whether candy contains citric acid!
The science behind the fun: Oil floats on water because it is less dense. When citric acid in candy combines with baking soda, a chemical reaction occurs which produces carbon dioxide gas bubbles. As the bubbles move up through the oil, they carry water and food coloring with them. Once the gas escapes into the air, gravity pulls the water and food coloring back down through the oil.to the bottom of the container.
Turn your kitchen table into the coolest mad science lab in the neighborhood. Click on the project name for a link to instructions and the “Science Behind the Fun.” Several of these projects can be found in my book “Kitchen Science Lab for Kids,” if you’re looking for a gift for your young mad scientist!
1. Frankenworms– Bring gummy worms to “life” using baking soda and vinegar.
2. Alien Monster Eggs– Make creepy, squishy monster eggs.
3. Oozing Monster Heads– Combine science and art to create Halloween fun.
4. Bag of Blood– Amaze your friends with this magical science trick.
9. Magic Potion– Make a color-changing, foaming potion using red cabbage and water.
10. Halloween Soda Explosion– Halloweenize the classic Diet Coke and Mentos explosion
11. Foaming Alien Blood– Bring the X-Files to your kitchen with this creepy green fake blood
12. Mad Scientist’s Green Slime– Because everyone loves slime
13. Homemade Fake Blood– It’s simple to make non-toxic fake blood in your kitchen.
14. Fizzy Balloons– Draw scary faces on balloons and blow them up using baking soda and vinegar.
If you have balloons, straws and string, you can send a balloon rocket shooting up a string to watch Newton’s third law of motion in action. As the air escapes the balloon in one direction, it sends the balloon rocket in the opposite direction! Art lovers will have fun making beautiful evaporation rings using vinegar, food coloring and cornstarch, and if you’re into engineering, order a small motor and some alligator clips to make a bristle robot!
Here’s a segment I did for TV last week, featuring of projects from Chemistry for Kids, which pairs the story of 25 scientists with hands-on projects related to their work! In the clip, I demonstrate how to collect essential oils from flowers, citrus or herbs using a crock pot and how to do a precipitation experiment similar to one Marie Curie used to extract radium from mining waste.
I joined the hosts of Twin Cities Live yesterday to show off three projects from my newest book! Chemistry for Kids is available everywhere books are sold!