ChemShorts for Kids  —  2013
Copyright 2013 by the Chicago Section of the American Chemical Society

by Kathleen Carrado Gregar, PhD, Argonne National Labs
kcarrado@anl.gov

Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.


January 2013

Crystal Snowflake Ornaments

Kids, learn how to cover a paper snowflake with crystals to make a glittering crystal snowflake decoration!  You will crystallize borax onto homemade paper snowflakes, in any size you like. You will need:  round paper coffee filters, borax, water, scissors, and food coloring (optional).

  1. Cut a paper snowflake (or other shape) from the coffee filter.  Go to this link  http://chemistry.about.com/b/2008/12/21/cut-out-science-decorations.htm for actual snowflake paper cut-out shapes.
  2. Have an adult partner prepare your crystal solution by stirring 3 tablespoons of borax into 1 cup of very hot water.  It's okay if there is a little undissolved borax. Add a drop of food coloring, if you want colored snowflake ornaments.
  3. Place the paper snowflake onto a plate or saucer. Have your adult partner carefully pour the crystal solution over the snowflake, making sure it is completely covered.  Try to leave any undissolved borax behind in the cup.
  4. Allow crystals to grow on the snowflake until you are satisfied with their size. Small crystals take about an hour to form. You can allow the crystals to grow overnight if you want larger crystals.
  5. Pour off the crystal solution and carefully dislodge the crystal snowflake from the plate. This is best done with a fingernail or butter knife. You can remove any crystals that are stuck in the holes of the snowflake.
  6. Allow the crystal snowflake to fully dry before removing it and hanging it.

Borax is a natural mineral with a chemical formula Na2B4O7 • 10H2O. The formal name for borax is sodium tetraborate decahydrate, but it’s more commonly known as sodium borate. It is one of the most important boron compounds.  Borax is found in laundry booster, certain hand soaps and in some toothpastes. You can find it as 20 Mule Team Borax (pure borax) in the laundry detergent aisle of stores.

Borax has many uses on its own, plus it is an ingredient in other products. Here are some uses of borax powder and pure borax in water:

Borax is an ingredient in several other products, such as: buffer solutions, flame retardants, teeth bleaching products, glass, ceramics and pottery, and enamel glazes.

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References:
Anne Marie Helmenstine at About.com: Chemistry
http://chemistry.about.com/od/holidayhowtos/a/Crystal-Snowflake-Ornaments.htm

 


February 2013

Homemade Essential Oil Air Fresheners

Kids, have you heard that necessity is the mother of invention?  For those of you with asthma who can use some help in the room-deodorizing department, there is hope. The answer is homemade, all-natural, essential oil powered, gel based air fresheners.  They smell great.  They last a good long time.  They are cheap to make.  They have five ingredients you can find at any grocery or department store.  And chemistry can explain how it works!

First a word about essential oils: they’re powerfully scented and a little goes a long way, so go easy on how much you add.  You don’t want to add more than 30 drops per air freshener until you know just how strong your oil is.  Here is a basic air freshener recipe, with a few favorite scent combinations below.

You’ll need:

Watch an adult partner do the following steps. Bring one cup of water to a boil in a small saucepan.  Sprinkle the gelatin over the boiling water and stir until smooth and all of the gelatin is dissolved. Add the salt and the second cup of cold water and stir. Set aside. Add essential oil and food coloring to the jar(s).  Quickly pour the hot dissolved gelatin over the essential oil and food coloring.  Stir until evenly colored. Allow to cool uncovered on a heat-proof surface. When cooled, keep covered until ready to use.  When ready to use, uncover the jar and place it wherever you want a lovely scent.

An essential oil is a concentrated liquid containing volatile aroma compounds from plants. An oil is "essential" if it carries a distinctive scent, or essence, of the plant. They are used in perfumescosmetics, and soaps, for flavoring food and drinks, and for adding scents to household cleaning products.

Gelatin is a translucent, colorless, flavorless solid derived from collagen.  It is found in gummi candiesmarshmallowsgelatin dessert, and some ice creamdip and yogurt.  Gelatin is classified as a food.  When you dissolve the gelatin powder in hot water, you break the weak bonds that hold the collagen protein chains together. Each chain is a triple-helix that will float around in the bowl until the gelatin cools and new bonds form between the amino acids in the protein. Scented oils and colored water fills in the spaces between the polymer chains, becoming trapped as the bonds become more secure. The gel is mostly water.

Some Scent Combinations:

sweet basil and lemon air freshener

rosemary orange air freshener

fresh pine scent air freshener

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References:
Thanks to Emily Neis for telling us about this idea.
http://www.foodiewithfamily.com/2010/03/17/homemade-essential-oil-air-fresheners/
http://chemistry.about.com/od/foodcookingchemistry/a/how-jell-o-works.htm


March 2013

Water Balloon Ice Gems

Kids, this is an easy way to make some decorations for your house if you live in a cold climate. You'll need water, balloons, food coloring, and outside temperatures below 25°F for at least two days.

Step 1. Fill

Open a balloon with one hand and drop 3-4 drops of food coloring into the dry balloon. Food coloring is affected by cold and may settle to one spot in your ice gem. Therefore there may not be a uniform color. Crystal clear gems are beautiful as well, so you don’t even have to add color. Secure the lip of the balloon over the lip of the kitchen or bathroom tap. Hold the lip of the balloon secure with one hand while you hold the weight of the balloon with the other hand. Fill the balloon with the coldest water you can get from the tap, and fill it slowly. Don’t overfill the balloon! Tie the balloon like you'd tie a normal water balloon. Don't worry if there's an air space at the top; it won't matter.

Step 2. Freeze

If it’s cold enough outside, that's the most convenient; otherwise, have an adult partner carve out enough space in a freezer. It’s wise to put something underneath the balloons. Though unlikely, the balloons might burst or stick to the ground or bottom of the freezer. Plastic grocery bags work fine. Make sure balloons rest on a flat surface, since you want the ice gems to have a flat bottom. Freeze for a day and then gently flip the balloons onto their side to continue freezing. They form ice toward the top of the balloon first, and flipping them onto their sides speeds up freezing the bottom half. Continue freezing for at least another day and night to ensure the core is completely frozen. After two days, check the balloon by gently shaking it back and forth. If you feel liquid sloshing around inside the gem, or see an air bubble moving around inside, put it back into the freezer or outside for another day.

Step 3: Unwrap

Now for the fun part! It's okay to unwrap your gems indoors, but make sure they're not in the warm air for too long. They start to melt fast, even with body heat. Take one at a time to a table with a regular-sized soup bowl. Gently remove the outer balloon coating, doing your best not to touch the surface of the gem (which instantly starts it melting.) The balloon and gem might have sharp, icy edges, so be careful. Each gem is different and unique. What will you find? After each one is unwrapped, use the bowl to transport the gem either into the freezer or outside.

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References:
Thanks to Milt Levenberg for sharing this idea.
http://faceless39.hubpages.com/hub/How-To-Make-Decorative-Ice-Gems


April 2013

Make Fake Glass

Kids, why aren’t people really hurt in movies when they appear to be thrown through glass windows?   To discover their secret you can make stage "fake" glass by heating sugar and spreading it onto a cookie sheet.

Be sure to have adult supervision when you do this activity!

What You Need:

What to Do:

  1. Spread butter onto a baking sheet or cover a baking sheet with baking (silicon) paper. Place the baking sheet in the refrigerator to chill it.
  2. Pour the sugar into a small pan on a stove and warm it over low heat.
  3. Ask an adult partner to stir the sugar continuously until it melts. Be patient because this will take a while. Use a candy thermometer to monitor the temperature of the melt.  Rremove the pan from the heat when the sugar turns clear (this is the "hard crack" stage on the thermometer). This will make a colorless transparent fake glass.
  4. If you heat the sugar just past the hard crack stage it will turn amber and it will make a colored translucent fake glass.
  5. Your adult partner should then pour the melted sugar onto the chilled baking sheet. Allow it to cool. You now have made candy glass.

The candy glass can be used as windows in dollhouses or gingerbread houses, or for lots of other things we can surely be creative in finding.

Tips:

Boiling water can be used to dissolve the sugar residue and speed clean-up.

If you like, the glass can be colored using food coloring. Add the coloring after the sugar has melted and has cooled slightly.

Be extremely careful because molten sugar is very hot, and can cause serious burns.

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References:

http://chemistry.about.com/cs/howtos/ht/fakeglass.htm

http://mimp.materials.cmu.edu/hst/Projects/2012/2012-Corcoran.pdf


May, 2013

Glowing Petroleum Jelly

Kids, what makes certain things glow under black lights?  First, let’s talk about the light. The reason black lights are called "black lights" is because they give off very little light that our eyes can see. Visible light contains the colors of the rainbow:  red, orange, yellow, green, and blue, to violet or purple. Beyond violet light in the spectrum is ultraviolet light, which our eyes cannot detect.  You can buy a black light for about $5-$10 in a novelty store or some large home repair stores, and probably other places around halloween.  These are the lights that look a dim purple when lit up, but cause some things around you to fluoresce, or light up with bright colors.  These days they come as incandescent bulbs, fluorescent tubes, and cold fluorescent lights.  The incandescent bulbs get very hot to the touch, so be careful around them.

First we’ll use petroleum jelly as a kind of invisible ink. Dip your finger into the jelly, then use your finger to write a message on the piece of paper.  When you’re finished, wipe any remaining jelly off your finger. Have the black light ready, then turn off the room lights and turn on the black light. Can you see the message? Why is something that you couldn’t see in room light now visible when you can’t see any light?

Can you think of a way to make your hands glow in the dark? If you have thin plastic gloves, put them on your hands (this is optional). Reach into the jar of petroleum jelly and scoop out enough jelly to cover both hands. Rub the jelly well over both hands, and then ask someone to turn off the lights in the room, and to turn on the black light. Hold your hand under the black light.  What do you see? If you prefer something less messy, just draw a picture on your hand with Vaseline, like a smiley face.  Turn on the black light in a darkened room to see your artwork.

If we can't see ultraviolet light, why does the petroleum jelly glow under the black light?  Most of the time when we look at an object, we see light reflected from the surface of the object. But with a black light, there isn't much visible light, so simple reflection of light doesn't account for how bright the jelly glows. Petroleum jelly contains substances called phosphors. A phosphor absorbs radiation, often in the ultraviolet, and emits it as visible light, in a process called fluorescence. So the phosphors in the jelly are absorbing the invisible ultraviolet radiation from the black light and emitting visible light.

Vaseline® Petroleum Jelly is a mixture of mineral oils, paraffin and microcrystalline waxes that, when blended together, create a smooth jelly that has a melting point just above body temperature.

With a little investigation, you might find many other things around your house that light up under black light.  Check out colored plastic parts, highlighter pens, and even powdered laundry detergent.  The detergent often has a whitener or optical brightener in it to make the clothes look whiter in daylight, and to replace optical brighteners added to the fabric while the piece is manufacturered.

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References:  http://scifun.chem.wisc.edu/homeexpts/vaseline.htm


June, 2013

Best Bubble Recipes

Kids, how often have you felt like blowing bubbles but couldn’t find a bottle of them around the house?  And are you tired of bubbles that pop as soon as you blow them?  A soap bubble consists of a thin layer of water trapped between two layers of soap molecules.  The tricks to longer-lasting, hardier bubbles are to add stability and to slow down evaporation. Here you will learn about secret ingredients that impart these properties.  All bubble solutions use a surfactant (soap), of course.  Soap is a simple, safe, inexpensive, and easy-to-find chemical.  One secret ingredient has these properties too, which is glucose or sucrose, simple sugars.  Sugar adds some stability to the bubbles.  Another commonly used ingredient is glycerin.  The glycerin acts like a thin layer of oil around the bubble’s surface, and slows down evaporation.
 
Compare these bubble recipes to see which work best for you, and then ask yourselves why.  Simply stir these ingredients together in large containers. 

Light corn syrup is glucose, and sugar is sucrose.  Both are simple sugars.  But compare how they perform in your bubble sizes and lifetimes to see if there are differences.

NOTES:

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References:

See ChemShorts November 1995 on the Science of Soap Bubbles for more info.

Marybeth Hamilton at http://www.babysavers.com/how-to-make-bubbles-for-kids-7-of-the-best-homemade-bubble-recipes/

Anne Marie Helmenstine at About.com Chemistry:
http://chemistry.about.com/od/bubbles/a/Bubbles-That-Dont-Pop.htm?nl=1


September 2013

Supercooled Slushy Science

Kids, here’s a way to cool off and amaze your friends by making a soda turn into a slushy on command. And all you need is some soda and a freezer! The slushy project works especially well with 16-oz or 20-oz carbonated soft drinks in plastic bottles.

Procedure

  1. Start with a room temperature bottle of soda pop. You could use any temperature, but it's easy to estimate how long it will take to supercool the liquid if you know your approximate starting temperature.
  2. Shake up the bottle and place it in a freezer. Do not disturb the soda while it is chilling or else it will simply freeze.
  3. After about 3-1/2 hours, carefully remove the bottle from the freezer. Each freezer is a little different, so you may need to adjust the time for your conditions.
  4. There are several different ways to start the freezing of the supercooled liquid. (a) Open the cap to release pressure, reseal the bottle, and turn the soda upside down, causing it to freeze in the bottle. (b) Slowly open the bottle, releasing pressure slowly, and pour the soda into a container, causing it to freeze into slush while you pour. You may pour the drink onto an ice cube to get it to freeze from the ice cube back toward the bottle. (c) Slowly pour the soda into a clean cup, keeping it liquid. Drop a piece of ice into the cup to initiate freezing. Here you can watch the crystals form outward from the ice cube.

How It Works Supercooling a liquid means to chill it below its normal freezing point without turning it into a solid. Although sodas contain ingredients besides water, they are dissolved in the water and so they don't provide nucleation points for crystallization to occur. The added ingredients do lower the freezing point of water (freezing point depression), so you need a freezer that gets well below 0°C or 32°F. You shake up the can of soda pop before freezing it in order to eliminate any large bubbles that could act as sites for ice formation.

Notes You can make instant slush in cans, too, but you can't see what is going on inside the can and the opening is smaller and harder to open without jarring the liquid.

If you don't have access to a freezer, you can use a large container of ice. Sprinkle a large quantity of salt on the ice to help make it extra-cold. Cover the bottle with the ice. The salt-ice mixture creates an example of freezing point depression.

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References:
Anne Marie Helmenstine at chemistry.about.com:
http://chemistry.about.com/od/ediblescienceprojects/a/Instant-Slushy-How-to.htm?nl=1


October 2013

Quick Cups of Crystals

Kids, this is a great way to quickly make a large amount of crystal needles!

In a cup or a small, deep bowl, mix 1/2 cup of Epsom salts (magnesium sulfate) with 1/2 cup of hot tap water. Stir for about one minute to dissolve the Epsom salts. There will still be some undissolved crystals at the bottom. You have created a "saturated" solution, which means the liquid has dissolved all of the salts that it can hold.

Place the cup or bowl into a refrigerator. The cup or bowl will fill with needle-like crystals within three hours.

If you would like to grow colored crystals, you can color the hot water first with a drop of food coloring.

Tips:

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References:

Anne Marie Helmenstine at Chemistry.About.com,
http://chemistry.about.com/od/crystalrecipes/ht/cupofcrystals.htm


November 2013

Make Dry Ice Bubbles

Kids, you can use sublimating dry ice to produce carbon dioxide gas to fill bubbles. Here we will give you three variations for this experience, beginning from simple and gradually getting a little more complex.

Small Bubbles. A small piece of dry ice can be used to produce cloudy bubbles that will last for a long time. Pour a little bubble solution into a bowl. If you don't have bubble solution, swish a small amount of liquid dishwashing detergent into water. Ask an adult partner to use tongs or gloves to pick up a piece of dry ice and add it to the bubble solution. That's it!

Giant Bubble. All you need to make a giant bubble is dry ice, bubble solution, a paper towel or cloth rag, and a little water. The dry ice sublimates to form carbon dioxide gas, which expands the bubble. Pour some water into a bowl. Have an adult partner add a piece of dry ice. The dry ice will make bubbles in the liquid.  Use a piece of paper towel or a rag that has been wetted with bubble solution to smear bubble solution across the whole top surface of the container. What happens?

Glowing Bubbles. You can make the bubbles glow by adding a little highlighter ink to the bubble solution. For the giant bubble version, you can try tonic water instead of tap water, and use a black light.

How It Works
Dry ice sublimes in air, meaning the solid carbon dioxide changes into carbon dioxide gas. This process occurs much more quickly in a bubble solution than in air. As the dry ice sublimes, the carbon dioxide vapor is caught inside the bubble solution. The bubble expands, but the cooled bubble solution does not evaporate quickly so the bubble lasts for a relatively long time.

Sometimes conditions are right for the bubble to stabilize at a given size. This happens because carbon dioxide is able to diffuse across the bubble surface. Sublimating carbon dioxide expands the bubble, but when the bubble expands its walls become thinner and leak more. Since more carbon dioxide can escape, the pressure is reduced and the bubble has a tendency to shrink back again. As long as the solution doesn't evaporate too quickly, the bubble may remain relatively stable until the dry ice is nearly gone. At that point the bubble will become smaller.

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References:

Anne Marie Helmenstine in About.com Chemistry:
http://chemistry.about.com/od/dryiceprojects/a/dryicebubbles.htm
http://chemistry.about.com/od/dryiceprojects/a/dryicebubble.htm

 


December 2013

Marbled Christmas Gift Wrap

Kids, it's really easy to make your own gift wrap which can then be a part of your holiday gifts! You can even add a holiday scent to the paper for an extra special touch.

MATERIALS. You'll need paper (regular printer paper is fine), shaving cream, food coloring or water-soluble paints, silverware, a shallow pan that's large enough for your paper, and a squeegee or paper towels.

PROCEDURE. Spread a thin layer of shaving cream in the bottom of the pan. You can use a spoon, knife or spatula, or even your fingers. All you need is a shallow coating. Dot the surface of the shaving cream with food coloring or paint or pigment. Use your imagination to pattern the colors. One option is to use the tines of a fork through the colors in a wavy fashion. But don't get too enthusiastic swirling your colors or else they will just run together. Lay your paper on top of the colored layer in the pan, and smooth the paper out over the shaving cream. Remove the paper and either squeegee off the shaving cream (wiping between passes) or wipe the shaving cream off with a dry paper towel. If you do this carefully then your colors won't run or distort.

Let your paper dry. If it starts to curl first, you can put a book or pan on top to flatten it out before it dries. The marbled paper will be smooth and slightly glossy. Neither the food coloring nor tempera paints should transfer off of the paper once it's dry.

HOW IT WORKS. The shaving cream has both soap and some water, among other ingredients. Use food coloring, paints, or other pigments that will dissolve in water. The soap (or surfactant molecules) will not penetrate the paper and can be wiped off, leaving the water-based color molecules behind in the paper, and also leaving a clean sheen on the surface.

NOTES. You can use any paper for this project and will get slightly different effects depending on your selection. You can use any shaving cream, too. If you use peppermint-scented shaving cream then you can make paper that smells like candy canes. And you can use any pigment you like, so be creative!

Food coloring and paints can stain skin and clothing. Wear protective smocks or use washable paint if you're concerned about staining your clothes.

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References:  Anne Marie Helmenstine at About.com Chemistry: http://chemistry.about.com/od/chemistryhowtoguide/a/marbledpaper.htm
http://www.wikihow.com/Paint-Marbled-Paper-Using-Shaving-Cream
http://www.incredibleart.org/lessons/middle/marbling.htm

Updated  11/27/13