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?
Seven weeks from today, my new book “Kitchen Science Lab for Kids: Edible Edition” hits shelves everywhere books are sold, and there are some great pre-order sales going on now! Kitchen Science Lab for Kids, Edible Edition gives you 52 delicious ideas for exploring food science in your own kitchen by making everything from healthy homemade snacks to scrumptious main dishes and mind-boggling desserts.
Here’s a sneak peek into the book….
When you step into your kitchen to cook or bake, you put science to work. Physics and chemistry come into play each time you simmer, steam, bake, freeze, boil, puree, saute, or ferment food.
Knowing something about the physics, biology, and chemistry of food will give you the basic tools to be the best chef you can be. The rest is up to you!
Monday April 22nd is Earth Day, so get outside and show our home planet some love! Whether you’re picking up trash or visiting a park, it’s always fun to throw some science into the mix.
Here are some of our favorite environmental science experiments. Just click on the experiment names for directions and photos. You can find more fun outdoor experiments in my books “Kitchen Science Lab for Kids” and “Outdoor Science Lab for Kids“ (Quarry Books.)
Homemade Sweep Nets: Make a sweep net from a pillowcase and a hanger to see what arthropods are hanging out in your favorite outdoor spaces.
Window Sprouts: Plant a bean in a plastic baggie with a damp paper towel to see how plants need only water and air to sprout roots and leaves. Here’s a short video demonstrating how to make a window garden.
Homemade Solar Oven: Using a pizza box, aluminum foil, plastic wrap, and newspaper, you can harness the sun’s energy to cook your own S’mores!
Nature Walk Bracelets: Wrap some duct tape around your wrist (inside out) and take a walk, sticking interesting natural objects like leaves and flowers to your bracelet. It’s a great way to get outdoors and engage with nature. Bring a bag along so you can pick up any trash you find.
Carbon Dioxide and Ocean Acidity: See for yourself how the carbon dioxide in your own breath can make a water-based solution more acidic. It’s the same reason too much carbon dioxide in Earth’s atmosphere can be bad for our oceans.
Plant Transpiration: See how trees “sweat” in this survival science experiment.
Earthworm Experiment: Do you know what kind of earthworms are living in your back yard?
Composting: Be a composting detective. Bury some things in your back yard (away from power cables) and dig them up in a few months to see how they look. Composting reduces methane gas emissions (a greenhouse gas) from dumps.
Diffusion and Osmosis: See for yourself how the chemicals we add to water, put on our streets to melt ice, and spray on our lawns and crops can move into our soil, ground water, rivers, lakes and oceans.
Solar Water Purification: This project illustrates the greenhouse effect and is a fun “survival science” experiment. Requires hot sun and some patience!
Citizen Science: Don’t forget about all the real environmental research projects you can participate in through Citizen Science programs all around the world!
For mores activities and games, check out NASA’s Climate Kids website, to see a kid-friendly diagram of the water cycle, click here, or just get outside and enjoy the beautiful planet that sustains and nurtures us.
Homemade pop rocks aren’t as fizzy as the ones you buy at the store, but they’re mighty tasty! Citric acid combines with baking soda to make carbon dioxide gas bubbles that get trapped in the candy. Adding extra citric acid and baking soda to the surface of the candy gives some extra fizz when you put them in your mouth. Trick your friends by adding a flavor that doesn’t match the color!
Warning: Ages 8 and up only. Extremely hot candy syrup. Adult supervision required.
2 cups sugar
1/4 cup water
1/2 cup corn syrup
a few drops of food coloring
1 tsp flavoring, like orange or cherry
1/4 cup citric acid + 1 tsp to sprinkle on in final step
1 tsp baking soda plus some to sprinkle on the candy
Step 1. Coat a the bottom of an inverted baking sheet with cornstarch.
Step 2. Boil sugar, corn syrup, and water, stirring until it reaches 300 degrees F.
Step 3. Remove the hot, melted candy from heat. Stir in food coloring, flavoring, 1/4 cup citric acid and 1 tsp baking soda.
Step 4. Very carefully, pour the mixture onto the baking sheet. Do not touch!!! Sprinkle 1 tsp. citric acid evenly over the surface of the candy.
Step 5. Let the mixture cool for at least 30 minutes and the break it into small pieces. Put some of the fragments in a plastic zip lock bag and use a hammer or rolling pin to crush them into tiny pieces or powder.
Step 6. Sprinkle on a little more baking soda and shake up in the bag.
Step 7. Enjoy the leprechaun pop rocks!
You can dye a rainbow of streaks in your hair using Kool-Aid drink mix. Practice on yarn first to perfect your technique!
Sheep’s wool and human hair are both made up of proteins called keratins, which can be dyed using chemical mixtures called acid dyes. These dyes are used to dye wool and alpaca, and some of the non-toxic ones can be used to dye human hair. Despite their name, they don’t actually contain acids. Instead, they require mild acid, such as citric acid or vinegar to be present in order for them to attach to proteins.
Kool-Aid drink mixes contain acid dyes that are perfect for dying keratin, and the color will wash away in a few washes. The mixes usually contain citric acid, but it helps to add vinegar as well to create an acidic solution. Colors will be most visible on lighter-toned hair or hair that has been chemically lightened, but you can dye dark hair too, by using more Kool-Aid mix.
Remember, Kool-Aid stains skin, fabric and other surfaces!
To dye yarn you’ll need:
100% wool yarn (white or cream, not cotton or synthetic fiber)
Kool-Aid drink mixes (powdered or liquid concentrate)
- Cut yarn into desired length and tie into bundles.
2. Soak yarn in warm water for 30 minutes.
3. In small containers, add enough vinegar to cover yarn and enough Kool-Aid to create intense colors.
4. After 30 minutes, put the wet yarn in the vinegar.
5. Soak for 30 minutes to overnight.
6. Remove yarn from dye, rinse well with cold water and hang to dry.
7. To make multi-colored yarn, soak yarn in vinegar and then squirt dye directly onto yarn. Let sit, rinse out and dry.
To dye streaks or the tips of your hair, shampoo and dry your hair. Skip the conditioner and put on an old shirt that can be stained.
Add the desired shade of Kool-Aid to vinegar in a bowl and soak the portions of your hair that you want dyed in the Kool-Aid mix for half an hour or so.
Rinse ends several times and dry. Remember that if your hair gets wet, it may transfer color to your clothes!
Use science to make your holidays shine! Here are a few fun ornaments adapted from projects in my book “STEAM Lab for Kids.” Basic instructions can be found below. Buy your own copy of “STEAM Lab for Kids” anywhere books are sold to learn more about the “Science Behind the Fun!” Happy Holidays!
LED Ornaments and Jar Globes:
To make LED ornaments, buy plastic jars or ornaments with removable bases. Use sculpting clay (the kind that won’t harden) to design a scene and add LEDs connected to a coin-cell battery to light your creation. LEDs can be ordered online. See images below.
Epsom Salt Crystal Ornaments:
(Warning: Hot liquids require adult supervision.) To make the Epsom Salt crystals, dissolve 3 cups of Epsom salts in 2 cups of water by heating and stirring until no more crystals are visible. This creates a supersaturated solution. Allow the solution to cool slightly. Hang pipe cleaners formed into snowflakes in jars or hollow ornaments and pour the solution in. When long, needle-like crystals have formed, remove the pipe cleaners from the jars. You can leave them in the ornaments, and drain the liquid.
To make a holidays version of the fizzing bath tablets in the video, we scented them with pumpkin pie spice and added a little more oil to incorporate the extra ingredients.
1 cup baking soda
¼ cup cream of tartar
3 Tbsp. coconut oil, melted to liquid
1 tsp. pumpkin spices
-Whisk together baking soda, cream of tartar and pumpkin spices. Slowly drizzle in coconut oil, mixing immediately. Stir for several minutes until you get a nice even mixture that holds together when you press it between your fingers. Add a little more oil if it is too powdery.
-Add a few drops of food coloring and mix again until the color is incorporated.
-Press the bath bomb mixture into a tablespoon and tap in on a tray to remove the bath tablet. If they don’t hold together, try adding a little more oil and mixing again. Dry the bath fizzies on a plate or cooking sheet and package them in cellophane bags or pretty baking cups for friends and family. Use the fizz bombs within a few weeks for maximum fizziness!
You can make larger “bath bombs” using molds for round ice cubes (which we found at Target.) Double or triple the recipes, gently press some mixture into each side of the mold, and mound a little extra on each side. Press the mold together to compress the bath bomb mixture into a single ball. Tap one side gently with the back of a spoon and gently open the mold to release that side of the sphere. Hold it in your palm and repeat with the other side to release the entire bath bomb from the mold.
The science behind the fun: The chemical name for baking soda is sodium bicarbonate , and cream of tartar is an acid called potassium bitartrate, or potassium hydrogen tartrate . When you mix them together in water, you create a chemical reaction that forms carbon dioxide gas bubbles! It’s interesting to note that at temperatures below 76 degrees F (25 C), coconut oil is a solid, but that at temperatures above this, it melts into a clear liquid. How does this affect your bath fizzies? Will they work in cold water as well as they do in warm water? Try it!
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.
Sodium alginate (Say it like you say algae!) is a substance found in the cell walls of brown algae, including seaweeds and kelp. Its rubbery, gel-like consistency may be important for the flexibility of seaweed, which gets tossed around on ocean waves.
Here on dry land, you can use sodium alginate to make edible balloon-like blobs that are liquid in the middle. We can thank scientists for this delicious project, since they discovered that a chemical reaction between sodium alginate and calcium causes the alginate to polymerize, or form a gel. In this experiment, the gel forms on the outside of a sodium alginate blob, where the chemical reaction is taking place. The inside of the blob remains liquid!
No heat is required for this experiment, making it safe and fun for all ages!
Sodium alginate and calcium lactate can be tricky to find at the grocery store, so you’ll probably have to order them online. But they’re not very expensive, and you’ll have lots of fun playing with them!
-a blender or hand blender (parental supervision required for small children)
-1/2 tsp sodium alginate
-2 tsp calcium lactate
-flavored drink drops, like Kool-Aid or Tang (optional)
-squeeze bottle or syringe for popping boba*
You can make these with juice, but if there is any calcium in the juice, you may end up with foam in your blender, since it may start to polymerize the sodium alginate when you blend it in.
- Add 1 and 1/2 cup water (or calcium-free juice) to the blender.
- To the water, add 1/2 tsp. sodium alginate.
- Blend for about a minute, and let rest for 15 or 20 minutes, or until the bubbles are gone.
- If you want to add flavor, divide the sodium alginate solution into small containers and stir in the flavor, like a squirt of Kool-Aid liquid.
- Add 4 cups of water to a clean, clear glass bowl or container.
- To the water, add 2 tsp. calcium lactate and mix until completely dissolved. This is your calcium lactate “bath.”
- To make edible water balloons, fill a spoon, like a tablespoon, with the sodium alginate solution, and slowly lower it down into the calcium lactate bath. You’ll see a gel begin to form. Gently turn the spoon so the sodium alginate falls off the spoon and into the calcium lactate.
- After about 30 seconds, you’ll be able to see a pale blob in the water. Leave it there for three or four minutes. You can make several edible balloons at once.
- When the blobs are ready, use a spoon to carefully remove them from the bath and put them in a clean bowl of water for a few seconds to rinse them off.
- Put your edible balloons on a plate and taste them. What do you think?
- *To make popping boba, add the fruit-flavored sodium alginate to a squeeze bottle or syringe. Drip the flavored sodium alginate into the calcium lactate as fairly large drops. It may take some practice to get uniform drops of the size you desire. When they’re solid enough to remove from the calcium lactate, rinse them gently and add them to your favorite drink. A small sieve works well for rinsing.
Now that you know how to polymerize sodium alginate with calcium, what else could you try? Can you make a foam in the blender? Can you make gummy worms in the bath using the rest of your sodium alginate solution? Can you invent something entirely new??? Try it!
Thank you to Andrew Schloss’s book Amazing (Mostly) Edible Science for the experiment inspiration! Adding the Kool-Aid and Tang drops to add a little flavor and color was our idea! (This blog post was first published on KitchenPantryScientist.com on May 3rd, 2016 and revised to add popping boba July 24th, 2018.)
Take your summer food game up a notch using… science! Sorbet recipe below. Vinaigrette recipe is in the post below this one.
Simple Freezer Strawberry Sorbet (adapted from Epicurious.com)
30 minutes hands-on prep time, 8 hours start to finish
*Parental supervision required for boiling sugar syrup
a shallow dish
1 quart strawberries
1/3 cup lemon juice
1/3 cup orange juice
1 cup sugar
2 cups water
What to do:
- Make a sugar syrup by bringing 1 cup sugar and 2 cups water to a boil in a heavy sauce pan. Boil for 5 minutes.
- Puree strawberries in a blender or food processor until smooth.
- Add strawberries, lemon juice and orange juice to the sugar syrup.
- Pour mixture into a shallow dish and cool for 2 hours in the refrigerator.
- Put the chilled sorbet mix in the freezer for 6 hours, stirring every hour.
- Enjoy your sorbet!
The Science Behind the Fun:
In sorbet, sugar acts as an antifreeze agent, physically getting in the way of ice crystal formation to keep crystals small, so that you don’t end up with one big chunk of ice. Pre-chilling the mixture before freezing it allows it to freeze faster, which also encourages smaller crystals to form.