With some basic supplies (including a bunch of food coloring for that red-white-and-blue), use these four activities to slip in a little science during your Fourth of July festivities—but don’t forget the eye protection!
In this cult-following of an experiment, work with your young scientists to uncover exactly what kind of reaction is caused by the combination of mentos and soda. Afterall, the Fourth of July is nothing if not explosive!
The eruption that takes place when Mentos are dropped into diet soda is not a chemical reaction but a physical reaction, meaning that the molecules that make up the materials undergo a molecular rearrangement to produce a physical change. The molecules are not chemically altered. As the Mentos sink in the bottle, the candy causes the production of more and more carbon dioxide bubbles, and the rising bubbles react with carbon dioxide that is still dissolved in the soda to cause more carbon dioxide to be freed and create even more bubbles, resulting in the eruption.
Supplies: a two liter bottle of Diet Coke; 2 rolls of Mentos mints; 1 piece of 8x10 inch paper, such as construction paper; tape; safety goggles
Steps:
Note: For younger scientists, proper adult supervision is required! Remove the lid from the Diet Coke and set the bottle of soda on a flat surface.
Roll the paper into a tube around a pack of Mentos mints to make sure the paper is the right size, tape it into place, and pull it off of the roll of mints.
Hold your finger over one end of the paper tube and have your child fill it up with Mentos mints. (It will probably hold a pack and a half of mints.)
Have an adult hold the tube of mints over the mouth of the bottle. Do a count down and when you shout “one,” quickly dump the mints into the bottle and stand back.
Suggestions for more science: Experimenting with older kids and have an open parking lot nearby? Try the “loading and launching” method of this activity, detailed here: How to Make a Diet Coke and Mentos Rocket.
And check out these two kits for more explosive experimentation: With Eisco Lab’s Film Canister Rockets Kit, you can launch a rocket with two simple ingredients—vinegar and Alka-Seltzer—which react to create gas inside a closed film canister. Check out this link to learn more about this kit and why this reaction works well enough to pop the lid off the canister, allowing the canister to launch into the air!
Introduce students in the most fun way to rocket science and concepts involving Newton's laws using Eisco Labs Bottle Rocket Launching Platform, which launches two-liter soda bottles over 100 feet into the air. Safety note: This is not a child's toy and appropriate safety precautions and adult supervision are required at all times.
Making rock candy is chemistry in action! In this experiment, the size of sugar crystals—even if you cannot see them—are manipulated to produce an array of textures. When you first combine the boiling water with the multiple cups of sugar, you create a supersaturated solution of sugar-water. As the hot water begins to cool, it can no longer hold the sugar, so the supersaturated solution begins to separate and the sugar crystals begin to cling to your skewer or string.
Ingredients: 2 cups of water, 6 cups of white granulated sugar plus some extra, food coloring (2 drops of food coloring per jar/cup)
Supplies: clean containers such as cups (try using these beakers!) or mason jars; something to grow the sugar crystals on, such as some string or a wooden skewer; something to hold your string or skewer away from sides of the jar and bottom of the jar, such as a pencil or some clothespins or paperclips; medium-to-large-sized saucepan; oven; mixing spoon
Steps:
Note: Proper adult supervision required! Put the measured water into the saucepan and heat it to boiling. Once the water is boiling, begin adding granulated sugar a little at a time.
Keep mixing and heating until the sugar is completely dissolved. This can take up to 20 minutes or so.
Once the sugar is dissolved, divide your supersaturated solution into each cup or glass jar. Add the food coloring now and make sure to mix well.
Dip your string or wooden skewer into the supersaturated solution. Anchor it to the top of the container using the pencil and/or clothespins/paperclips. Make sure the string isn’t touching the sides of the jar or the bottom of the jar.
Put your sugar-water solution somewhere safe to sit for a few days. Watch and wait for your sugar crystals to grow. These are your rock candy crystals.
Enjoy your homemade rock candy!
Why do the crystals form? As the solution cools down, this is when we see sugar crystals form, and this is explained by Le Châtelier’s principle: A decrease in temperature causes a system to generate energy in an attempt to bring the temperature up. Because the formation of chemical bonds always releases energy, more sucrose molecules will join the crystal in an attempt to increase the temperature.
Suggestions for more science: Ask your kids the following questions to prompt additional approaches to the experiment: What kinds of structures can you form with the rock crystals? Stalactites? Stalagmites? Can you flavor your sugar crystals?* How does temperature affect the outcome of the sugar crystals? Do sugar crystals grow better with the supersaturated solution made from boiling water, or can you use the same ratio of sugar to water, but without the boiling?
* Yes, by adding about 1 tsp of vanilla extract to the sugar solution after it has been boiled before it begins to cool.
Want to grow your own crystal “garden”? Check out Innovating Science’s "Silicate Garden" chemistry kit. The kit has colored crystals that grow plant-like structures when added to a clear silicate solution in a glass jar or beaker.
Using the reliable reaction of baking soda and vinegar, this experiment is going to be an activity your kids will not soon forget. As the carbonic acid begins to decompose, it creates carbon dioxide gas. This gas expands and fills the Ziploc bag which then causes the bag to explode in order for the building pressure to be released.
Supplies: white vinegar, baking soda, cornstarch, food coloring, tissue paper (toilet paper, kleenex, etc.), measuring cup, tablespoon, quart-sized Ziploc bags, tools for painting with the chalk paint (e.g., large bristle or foam paint brushes)—or just use your hands!
Steps:
Fill each Ziploc bag with 1 cup cornstarch and 1 cup vinegar. Add a few drops of any color food coloring to each bag.
Seal the bags and mix with your hands until cornstarch is dissolved. Set bags aside.
Begin making baking soda bombs by placing 1 Tbsp. baking soda onto a square of toilet paper and folding it so the baking soda won’t spill out. Make one bomb for each Ziploc bag.
Outside, on a flat paved surface, open one corner of the Ziploc bag and drop in the baking soda bomb.
Quickly seal the bag back up.
Shake the bag gently to release the baking soda and place it on the ground.
Watch as the bag fills with gas and then explodes. Note: Make sure kids stay a safe distance away so the mixture does not get in their eyes upon explosion.
Manipulate the paint bags of erupting sidewalk chalk paint to make some chalk art!
Suggestions for more science: Take the opportunity to explore the scientific method. Have your kids make hypotheses as to what will happen when they mix ingredients together. Then perform the experiment again, only with a slight change, and see what changes. For instance, ask: What happens if you change the amount of baking soda? Why did some bags take longer to fill with gas? Can the mixtures be reused by just adding more baking soda? Why or why not? Try using water instead of cornstarch and note the differences.
You are going to be making three batches of slime for this activity! We made a single batch each of blue, red, and clear with silver glitter slime. You could also add in a white glue slime for a neat look (replace silvery clear slime). The recipe below makes one batch of homemade slime.
Supplies: 1/2 cup of clear Elmer's Washable School Glue (white Elmer’s Washable Glue works as well), 1/2 cup of water, food coloring, 1/2 tsp baking soda, 1 Tbsp saline solution (can be found in eye care section of drug/grocery stores), 3 cups of foam shaving cream
Steps:
Add foam shaving cream to a bowl.
Pour in glue and stir to combine.
Add food coloring as desired.
Add baking soda and stir.
Add in the saline solution. This will begin the reaction that turns the foam into slime!
Stir until the mixture begins to pull away from the bottom and sides of the bowl.
Squirt a few drops of saline solution on your hands and knead your slime. You can knead it in the bowl or pick it up and knead it. Keep kneading! Even though the mixture will seem messy, kneading will improve consistency as well as reduce the stickiness. Don’t go crazy adding saline solution until you have kneaded it well as this can make your fluffy slime rubbery.
Once you have red, white, and blue colors made, you can get busy swirling them together. I like to stretch them out in strips next to each other and let them slowly combine. Pick up from one end, and let gravity help the swirl form!
Incorporate more advanced chemical principles into your at-home experiments or in your school lab (with the proper safety gear!) with these three kits from Innovating Science:
Using the Underwater Fireworks Chemical Demonstration Kit, produce flashes of light (a.k.a. Independence Day mini-fireworks?) by placing calcium carbide in a cylinder containing water. A reaction will occur, producing acetylene gas bubbles. After placing a plastic tube from a chlorine gas generator into the cylinder, bubbles of acetylene and chlorine collide to produce flashes of light.
With the Innovating Science Forming Red White and Blue Kit, you can introduce your scientists to a number of chemical reactions, including a complex ion formation (for teaching about reversible chemical reactions, equilibrium and Le Chatelier's Principle), the double replacement reaction, and the formation of Prussian blue.
Finally, the Innovating Science The Oxidation-Reduction Flag (Redox Flag Kit) offers a fascinating and vivid demonstration of the power of redox (reduction-oxidation reaction) reactions in which the participant sprays a reactant on a colorless paper that has been pretreated with two different chemicals and observes the resulting color changes.
