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?
Repost from Dec.19th, 2010 (Photos from Kitchen Science Lab for Kids, Quarry Books 2014)
Have you ever gotten a shock from a doorknob after shuffling across a carpet? The term “static electricity” refers to the build-up of a positive or negative electrical charge on the surface of an object. In this case, the charged object is your body. You feel an electric shock as the charge you’ve collected from the carpet jumps from your hand to the metal doorknob.
Tiny particles called electrons have negative charges and can jump from object to object. When you rub a balloon on your hair, or a comb through it, many of these electrons are stripped from your hair and move to the balloon or comb giving it a negative charge (and often leaving your hair all positively charged and standing up as the strands try to avoid each other.)
The negatively charged balloon or comb then makes a great tool for making electrons jump around!
You can easily make a contraption called an electroscope using:
-some thin aluminum foil or mylar (the shiny stuff balloons and candy wrappers are made from)
-a balloon or comb.
- Cut the cardboard to fit over the mouth of the jar, poke the nail through the cardboard, tape on two long, thin strips of foil or mylar (see photo) and place the whole thing in the jar so the foil strips hang down, touching each other.
2. Charge your balloon or comb by rubbing it on your hair or clothing to give it a negative charge. Bring the charged object close to the nail head. You don’t even have to touch it!
What happened? Some negatively-charged electrons jump from the comb to the nail and into the strips of foil. The negative charge on the comb will push electrons (which are also negatively charged) down to the foil/mylar and give both strips a negative charge. The two strips try to move away from one another as the like charges repelled each other.
What happens when you make the strips out of different materials like paper? Are there other charged objects you can use to make your foil strips “dance”?
You can also bend a thin stream of water from the faucet by holding your charged comb next to it. The water is uncharged and is pulled toward the negative charge of the comb.
Try making small pieces of tissue paper float or dance by holding a charged comb or balloon next to them! We filled an empty soda bottle with tiny pieces of foil and made them jump around with a charged comb held close to the bottle.
(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.
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:
One of the best things about doing science in the summer is that you can take the mess outdoors, and clean it up with a hose. So what are you waiting for? Grab the baking soda, vinegar, food coloring, cornstarch and balloons and head outside for some instant off-screen fun. Share photos of your experiments on Twitter and Instagram using the hashtag #ScienceMess!
Here are some ideas to get you started, but you can find lots more on this website and in my new book Outdoor Science Lab for Kids!
Sidewalk Frescoes with Cornstarch Goo
Solar Heat Beam
Have fun experimenting! And don’t forget to clean up your mess!
This summer, get off screens and get outside!
Outdoor Science Lab for Kids: 52 Experiments for the Yard, Garden, Playground and Park hit real and virtual bookshelves this week! To celebrate, I’m posting this video we took a few weeks ago of one of my favorite experiments from the new book.
Can’t wait for your copy of the book to arrive before you try this out? Here’s how to make water rockets.
As I was trying to think of a science experiment to do with Peeps, I remembered seeing a marshmallow puff up to twice its normal size in a vacuum chamber, which was pretty cool.
Since I don’t have any way to create a mechanical vacuum at home, I decided to try using a wine pump to inflate a peep and discovered that it is extremely hard to get a Peep into a wine bottle. Even the bunny Peeps are too big to push in without maximum destruction!
So, I went bottle hunting and found that Smucker’s syrup bottles and Martinelli’s apple juice bottles have big enough mouths to accommodate Peeps of the chick or bunny variety, but still work with wine pumps. Here’s what happened!
To puff up a Peep, you’ll need
-a clear, empty bottle that fits both a Peep and a wine pump (see above.)
-a wine pump with a matching rubber vacuum cork
-Peeps (or marshmallows)
- Put a Peep or two in the bottle. If it’s sticky, coat the sticky spot with a little bit of sugar. Try to squish it as little as possible when pushing it into the bottle.
- Put the rubber vacuum cork in the bottle to form a tight seal.
- Pump air out of the bottle until your Peep has grown as much as possible
- Release the vacuum to see it shrink back to normal size.
The Science Behind the Fun:
Peeps contain corn syrup, gelatin and food coloring, but they are mostly made up of air bubbles. The air trapped in the bubbles is at atmospheric pressure. When you pump air out of the bottle, the pressure in the bottle drops. Gases expand under lower pressure, and the air in the marshmallow bubbles is no exception. The bubbles expand inside the stretchy corn syrup and gelatin (get bigger), making the Peep puff up.
Oil and water don’t mix, which comes in handy for this fun science experiment! Play with density and chemical reactions when you try this foaming, bubbling experiment that uses an effervescent tablet like Alka-Seltzer to make carbon dioxide bubbles ooze up through a thick layer of oil. (Adult supervision required, since Alka-Seltzer contains aspirin.)
Fill a bottle 1/4 full with water or vinegar*. Add food coloring (or red cabbage juice) to the water or vinegar.
Fill the bottle almost to the top with vegetable (or other) oil. Note how the oil floats on the water, since it’s less dense.
Optional: Add cut-up plastic Easter basket grass, glitter, plastic beads, or other items you think might float on the water layer, but sink through the oil.
Finally, add an effervescent tablet to the liquid in the bottle and watch the chemical reaction. When the citric acid and sodium bicarbonate (baking soda) in the tablet react with the water and each other, they make something new: carbon dioxide gas, or CO2. The CO2 bubbles carry some of the colorful liquid up through the oil with them, but the dense liquid quickly sinks back down to the bottom.
*Vinegar reacts with the sodium bicarbonate the Alka-Seltzer, making extra carbon dioxide bubbles!
For a fun variation, put a balloon over the top of your bottle after adding the Alka-Seltzer to trap the carbon dioxide gas and inflate the balloon. If the balloon looks like it’s about to pop, remove it from the bottle.