To make a battery, you need two oppositely charged electrodes (materials that pass electrical current from one thing to another) and an electrolyte (a liquid that allows charged atoms to travel through it.)
If you stick a zinc (galvanized) nail and a copper wire side by side into a lemon, but not touching each other, they act as electrodes. The lemon juice acts as the electrolyte.
A chemical reactions occurs between the zinc electrode and the acidic lemon juice, resulting in a second chemical reaction at the copper electrode. If you attach the two electrodes to a metal wire, electrons from the chemical reaction will flow through the wire from the zinc to the copper, creating an electric current. We used a tool called a mutimeter to connect the two electrodes and measure the current flowing through the wire.
To make a lemon battery, push a zinc nail and a piece of copper into a lemon, side by side, but not touching. You can use a copper wire or a penny.
Touch the two ends of a multimeter to each of the electrodes to see how much current you’re generating. (See image below.)
Test how changing the distance between the two electrodes changes the current. What else could you try?
(Re-post from April 14, 2016)
I love traditional tie-dye, but it’s fun to do this experiment that uses permanent markers and rubbing alcohol to make bright, gorgeous designs that mimic tie-dye, more easily, and with less mess.
This experiment was created by Bob Becker, a chemistry and AP chemistry teacher at Kirkwood High School in Kirkwood, MO. (To find a few of the original experiments I invented, check out Frankenworms, Sugar Cube Fizz Bombs, Homemade Window Stickies, Foaming Slime, and Cornstarch Frescos.)
Here’s a video from my YouTube channel on how to do this experiment, so kids can “watch and do.”
To play with permanent marker tie dye, you’ll need:
-permanent markers (like Sharpies)
-cotton items to decorate, like tee-shirts, socks, or dish towels
-rubbing alcohol (isopropanol)*Read warning labels. Parental supervision is required, since rubbing alcohol is poisonous if swallowed. Do this experiment in a well-ventilated area, and do not expose your artwork to heat until is is COMPLETELY dry, since rubbing alcohol and its fumes are flammable.
-containers like plastic cups or jars
To make your designs, stretch the cotton over the mouth of a jar or cup and secure it with rubber bands. (See video above.)
Use permanent markers to make several dime-sized dots of different colors on the stretched cotton.
Slowly drip rubbing alcohol onto the spots of color until the alcohol starts to soak outward, carrying the ink with it.
Allow your design to dry overnight. When completely dry, hang your shirt in the sun, or put it in the dryer for 15 minutes to set the color. Wash separately from other clothes, just in case!
The Science Behind the Fun: Pigments are molecules that give things color. The pigments in permanent markers are trapped in ink compounds that are insoluable in water, which means that they won’t dissolve in water. However, if you add a solvent, like rubbing alcohol, or isopropanol, to permanent markers, it dissolves the ink. As the alcohol moves through the cloth you are decorating, it carries the pigments along with it. Small pigment molecules move faster than big ones, so the colors sometimes separate into their different color components as they move through the cloth. The alcohol evaporates into the air, leaving the ink in the fabric, and since it is still insoluable in water, it won’t come out when you wash it.
Enrichment: What happens if you draw lines, concentric circles or different shapes on your designs? Can you layer colors and watch them separate? What if you add rubbing alcohol next to the color, instead of directly on it? How many drops of alcohol do you have to add to a dime-sized color spot before it starts to expand?
Remember this homemade snow candy from Laura Ingalls Wilder’s classic “Little House in the Big Woods?” You can make the same amazing maple treats using heat evaporation and quick cooling in the snow, or on crushed ice cubes.
Here’s how to make the candy, along with some candy-making science, straight from the pages of my new book, “Outdoor Science Lab for Kids,” which you can order from your favorite book retailer by clicking here.
-1 cup pure maple syrup
-fresh, clean snow
Safety Tips and Hints:
-Hot sugar syrup can cause burns. This experiment must be done with adult supervision.
-Allow candy to cool completely before tasting.
-Only use pure maple syrup for the best results.
Step 1: Go outside and scout out a spot with some clean snow several inches deep for making your candy. Alternately, collect and pack down a few inches of fresh snow in a large, flat container, like a casserole dish. (You can use crushed ice cubes if you don’t have snow.)
Step 2. Boil the maple syrup in saucepan, stirring constantly until it reaches around 235-240 degrees F (soft ball stage.)
Step 3. Remove the maple syrup from the heat and carefully pour it into a heat-resistant container with a spout, like a Pyrex measuring cup.
Step 4. Pour wiggly candy lines into the snow to freeze them into shape.
Step 5. When you’re done, remove the candy from the snow with a fork.
Step 6. Eat your candy right away, or let it warm up and wind it around sticks or skewers to make maple lollipops. Enjoy!
The Science Behind the Fun:
Maple syrup is made from watery tree sap boiled to evaporate most of the moisture it contains when it’s first tapped from a tree. Following evaporation, the syrup that remains is mostly made up of a sugar called sucrose, but it also contains smaller amounts of glucose and fructose.
Naturally, other organic compounds are also present in tree sap, giving syrup from different areas unique flavors. Syrup collected earlier in spring when it is cold tend to be light in color and have a mild flavor. As the days get warmer, microbes ferment some of the sugar in the syrup, making it darker and giving it a more robust taste.
In this experiment, you heat maple syrup, evaporating even more water. A super saturated solution forms, which holds more sugar molecules in the liquid than would be possible if you evaporated the water at room temperature.
When you pour the supersaturated sugar into the snow, it cools quickly, forming some sugar crystals to give the maple candy a soft, semi-solid consistency. Heating the syrup to a higher temperature will evaporate more water, resulting in even more crystal formation in the cooled syrup, making it harder to bite. If you carefully evaporate all of the water from maple syrup, you’ll be left with pure maple sugar crystals.
-Try collecting some syrup from your pan at several different temperatures and compare the resulting snow candy for texture, color and consistency.
-Can you do the same experiment with other sugar syrups, like molasses or corn syrup?
-Try to make maple sugar.
Crying over broken candy canes? Cry no more. Make art!
My publisher recently sent me a copy of “Amazing (Mostly) Edible Science,” by Andrew Schloss. There are tons of fun experiments in the book, but Candy Cane Origami seemed like a perfect one to try during the holidays.
*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!
Buying gifts is fine, but it’s more fun to make them. This year, we decided to make botanical gifts for the adults on our list, and slime kits for the kids.
To make a slime kit, you’ll need:
-glitter glue (optional)
-Borax laundry detergent
-small plastic sample cups or paper cups (optional)
-jars with lids
-a small plastic bin or shoe box
-extra glitter (optional)
Label the jars and fill as follows:
- Bouncy Ball Mix (fill with glue)
- Slime Mix (fill with equal parts glue and water, mixed well)
- Borax detergent (fill with powdered detergent)
- Cross-Linking Solution (leave empty)
- optional-Sparkly Bouncy Ball mix (fill with glitter glue)
- optional-Sparkly Slime Mix (fill with equal parts water and glitter glue, mixed well)
Make an instruction sheet for the kit. (Print out the info below, or copy it onto a card.)
To make slime:
- Fill Cross-Linking Solution container with warm water. Add about 2 tsp Borax per 1/2 cup water to the container. Mix well. (Don’t worry if all the Borax doesn’t dissolve!)
- Add a few spoonfuls of Ball Mix or Slime Mix to a small plastic cup or paper cup.
- Add a drop or two of food coloring to the cup. Stir.
- Add 3 spoonfuls of the Cross-Linking Solution to your ball mix or slime mix and stir well.
- If the slime still feels too sticky, add a little more Cross-Linking Solution.
- Remove your completed slime from the cup.
The Science Behind the Fun:
Glue is a polymer, which is a long chain of molecules linked together, like a chemical chain. The polymer formed by water and glue is called polyvinyl acetate.
The Borax solution is called a cross-linking substance, and it makes the glue polymer chains stick to each other. Eventually, all the chains are bound together and no more cross-linking solution can be taken up.
To finish the slime kit, fill the plastic bin with the ingredients you put together, including jars of ingredients, instructions, plastic spoons, and mixing cups (optional.)
(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.
We have bags full of candy at our house, and I’d like to see them disappear as quickly as possible. Here are a few science experiments we tried, substituting candy for other ingredients:
Candy Chromatography: We put candy in water and used coffee filters to separate out the colors, via capillary action.
Candy-drinking plants? We dissolved candy in warm water and added white carnations with cut/split stems to see whether they’d change color as the flowers drew the water up into their petals.
Candy Vegetable Vampires: We tried the same experiment with Napa Cabbage, via the Vampire Vegetables experiment in Kitchen Science Lab for Kids.
We’re also going to freeze candy in ice and make Tie Dye milk with Skittles!
What could you try with your candy?
Here are ten quick and easy experiments to make your Halloween even more fun and memorable!
Click on these links for instructions on how to make:
Here are a few of my favorites!
You can find more experiments by scrolling down on my website!
We had a great time playing with dry ice on WCCO TV this morning. I showed viewers how to make spooky Halloween decorations (hot water, food coloring and dry ice), carbonate beverages, inflate a balloon, and even make a spoon “sing.”
Dry ice is literally really cool, which is why you have to wear gloves to handle it. It’s made from frozen carbon dioxide gas, and as it warms up, it goes from the solid to liquid state instantly, skipping being a liquid altogether in a process called sublimation. As it becomes a gas, it cools water molecules in the air around it, making fog. And if you add it to a liquid, it carbonates the liquid with bubbles.
To make dry ice, you have to get carbon dioxide gas really cold and put it under pressure so that it goes instantly from the gas phase to the solid phase in a process called deposition. Here’s a video of a machine that makes dry ice pellets:
If you’ve ever seen the X-Files, you know that foaming green alien blood is pretty scary.
It’s simple to use kitchen table chemistry to mix up your own batch of green alien blood with corn syrup, green food coloring, water and baking soda.
Just add vinegar (tell your friends it’s water) to make it foam.
2 Tbs corn syrup
1 tsp baking soda
green food coloring
1/2 tsp water
When you want to make your slime foam, add a few tsp of vinegar.
You could make the same thing with red food coloring and call it vampire blood!
The Science Behind the Fun: When you add baking soda (sodium bicarbonate) to vinegar (acetic acid), there’s a chemical reaction that creates carbon dioxide gas bubbles!
Experiment created by Liz Heinecke at KitchenPantryScientist.com