Monthly Archives: April 2013

How to Make Green Fire

Have you ever watched Harry Potter and the Chamber of Secrets and wanted to make that green fire they use for wizard transport? Well Harry Potter fans, you’ll be happy to know that It’s easy to make brilliant green fire. This cool chemistry project, (oh sorry… alchemy project), requires only two household chemicals.

WHAT YOU NEED:

  • Boric Acid; (Medical grade boric acid can be found in the pharmacy sections of some stores for use as a disinfectant. It is a white powder. It’s not the same chemical as borax. I suggest using Enoz Roach Away™, which is 99% boric acid, sold with household insecticides.)
  • Heet™ Gas Line Antifreeze and Water Remover; (Heet™ is sold with automotive chemicals.)
  • Metal or Stoneware Container
  • Lighter

WHAT TO DO:

  1. Pour some Heet™ into the container. How much you use will determine how long your fire will burn. I used about a half cup of Heet™ for approximately 10 minutes of fire.
  2. Sprinkle some boric acid into the liquid and swirl it around to mix it up. I used 1-2 teaspoons of powder. It won’t all dissolve, so don’t worry about some powder at the bottom of the container.
  3.  Set the container on a heat-safe surface and ignite it with a lighter. There is a video on about.com to see the expected result. Here’s the link: http://video.about.com/chemistry/Green-Fire.htm

Green Fire Tips & Safety Information:

  • Boric acid is a relatively safe household chemical. You can rinse the residue remaining in the container down the drain.
  • This is an outdoor project. There isn’t a lot of smoke produced, nor is it particularly toxic, but the heat is intense. It will set off your smoke alarm.
  • Be sure to set your container on a heat-safe surface. Similarly, don’t use any container that might shatter dangerously. Use metal or possibly stoneware, not glass, wood, or plastic.
  • Heet™ is primarily methanol (methyl alcohol). You could try this project with other types of alcohol. Possibilities include ethanol, such as vodka or Everclear, or isopropyl alcohol (rubbing alcohol). You might also try other common household metal salts for different flame colors.
  • For example, I substituted rubbing alcohol (isopropyl alcohol) for the Heet™. The result was a fire that alternated from orange to blue to green. It wasn’t as spectacular as the Heet™ fire, but it was still pretty cool.
  • The green fire could be used as a stunning Halloween decoration in a cauldron or possibly inside a jack-o-lantern.
  • Keep the chemicals for this project out of reach of children or pets, since methanol is harmful if swallowed. Read and follow any safety precautions listed on the labels of the specific products you use.
Advertisements

Make Your Own Rock Candy

rock candyWHAT YOU NEED:

  • A wooden skewer (you can also use a clean wooden chopstick)
  • A clothespin
  • 1 cup of water
  • 2-3 cups of sugar
  • A tall narrow glass or jar

WHAT TO DO:

  1. Clip the wooden skewer into the clothespin so that it hangs down inside the glass and is about 1 inch (2.5 cm) from the bottom of the glass.
  2. Remove the skewer and clothespin and put them aside for now.
  3. Get a helpful adult!
  4. Pour the water into a pan and bring it to boil.
  5. Pour about 1/4 cup of sugar into the boiling water, stirring until it dissolves.
  6. Keep adding more and more sugar, each time stirring it until it dissolves, until no more will dissolve. This will take time and patience and it will take longer for the sugar to dissolve each time.Be sure you don’t give up too soon. Once no more sugar will dissolve, remove it from heat and allow it to cool for at least 20 minutes.
  7. NOTE: While it is cooling, some peole like to dip half of the skewer in the sugar solution and then roll it in some sugar to help jump start the crystal growth. If you do this, be sure to let the skewer cool completely so that sugar crystals do not fall off when you place it back in the glass.
  8. Have your friendly ADULT carefully pour the sugar solution into the jar almost to the top. Then submerge the skewer back into the glass making sure that it is hanging straight down the middle without touching the sides.
  9. Allow the jar to fully cool and put it someplace where it will not be disturbed.
  10. Now just wait. The sugar crystals will grow over the next 3-7 days.

Want colored rock candy? Add food coloring to your sugar water and make sure sure that it is pretty dark in color for the best result.

HOW IT WORKS:

    When you mixed the water and sugar you made a SUPER SATURATED SOLUTION. This means that the water could only hold the sugar if both were very hot. As the water cools the sugar “comes out” of the solution back into sugar crystals on your skewer. The skewer (and sometimes the glass itself) act as a “seed” that the sugar crystals start to grow on. With some luck and patience you will have a tasty scientific treat! Enjoy!

Magic Levitating Orb: You Won’t Believe Your Eyes!!!

YOU WILL NEED:

  • 1 inch (2.5 cm) wide PVC Pipe about 24 inches (60 cm) long. You can also use a regular balloon if you do not have PVC pipe.
  • Mylar tinsel for Christmas trees. There are many types of tinsel – you should look for the thinnest and narrowest possible. Look for one that’s about 1 millimeter wide. If it is much wider than that, the orb may be too heavy to levitate. (Visit sciencebob.com to get the tinsel if you can’t find any around).
  • A head of clean, dry hair
  • Scissors

WHAT TO DO:

1. Arrange 6 strands of Mylar together and tie them together in a knot at one end.
2. Tie them together again about 6 inches (15 cm) from the first knot.
3. Cut the loose Mylar strands off just past each knot.
4. Charge the PVC pipe by rubbing it back and forth through your hair for 10 seconds.
5. Hold the Mylar orb (by the knot) above the charged pipe and let it drop and touch the pipe.
6. It should repel away and start floating. If the tinsel keeps sticking to the pipe, the tinsel is probably not thin enough and you will need to try another kind of tinsel or order some from sciencebob.com (You will usually have to “recharge” the pipe before each levitation.)

HOW IT WORKS:

It’s all about static charges. Similar static charges repel away from each other. When you rub the pipe in your hair you give the pipe a negative static charge. The orb is attracted to the pipe at first because the orb has a positive charge. As soon as the orb touches the pipe, it picks up a negative charge. Since the pipe is negative and the tinsel orb is now negative, they repel away from each other and the orb levitates! The orb will also take on more of a “ball” appearance when charged since all the tinsel strands are repelling away from each other. Did you notice the orb is attracted to other objects around you – including you? That is because most objects (including you) have a positive charge.

Make it an experiment:

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

1. Does the number of Mylar strands affect how well the orb levitates?
2. Do different materials (hair, fur, wool) build up better static charges?
3. How long does the static charge last / how can you make it last longer?
4. Do different widths of pipe affect the floating ability of the orb?

Note: The tinsel used and sold at sciencebob.com is BriteStar tinsel “icicles.” It may be hard to find this kind of tinsel, since most stores have tinsel that is too thick. At sciencebob.com, you can get 1,000 strands of tinsel for 95 cents (plus shipping)! That means you can let others try the experiment, too.

 

Elephant’s Toothpaste

elephant's toothpasteYOU WILL NEED:

  • A clean 16 ounce plastic soda bottle
  • 1/2 cup 20-volume hydrogen peroxide liquid (20-volume is a 6% solution, ask an adult to get this from a beauty supply store or hair salon)
  • 1 Tablespoon (one packet) of dry yeast
  • 3 Tablespoons of warm water
  • Liquid dish washing soap
  • Food coloring
  • Small cup
  • Safety goggles

NOTE: The Elephant’s Toothpaste you will be making will overflow the bottle. Be sure to either cover your work surface or place a tray underneath the bottle.

WHAT TO DO:

1. Hydrogen peroxide can irritate skin and eyes, so put on those safety goggles and ask an adult to carefully pour the hydrogen peroxide into the bottle.

2. Add 8 drops of your favorite food coloring into the bottle.

3. Add about 1 tablespoon of liquid dish soap into the bottle and swish the bottle around a bit to mix it.

4. In a separate small cup, combine the warm water and the yeast together and mix for about 30 seconds.

5. Now the adventure starts! Pour the yeast water mixture into the bottle (a funnel helps here) and watch the foaminess begin!

HOW IT WORKS:

Foam is awesome! The foam you made is special because each tiny foam bubble is filled with oxygen. The yeast acted as a catalyst (a helper) to remove the oxygen from the hydrogen peroxide. Since it did this very fast, it created lots and lots of bubbles. Did you notice the bottle got warm. Your experiment created a reaction called an Exothermic Reaction – that means it not only created foam, it created heat! The foam produced is just water, soap, and oxygen so you can clean it up with a sponge and pour any extra liquid left in the bottle down the drain.

This experiment is sometimes called “Elephant’s Toothpaste” because it looks like toothpaste coming out of a tube, but don’t get the foam in your mouth, (or in an elephant’s mouth!)

Make it an experiment: 

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

1. Does the amount of yeast change the amount of foam produced?
2. Does the experiment work as well if you add the dry yeast without mixing it with water?
3. Does the size of the bottle affect the amount of foam produced?

Bob the Bouncing Blob

You don’t have to name your blob Bob. It might be more of a Bill, or a Babette.

WHAT YOU NEED: paper towels, 2 small plastic cups, measuring spoons, white craft glue, Epsom salt, warm water, plastic spoon, Ziploc bag

WHAT TO DO:

  1. Cover your work surface with two layers of paper towels. 
  2. Put 1 tablespoon of glue into one cup.
  3. Put 1/2 teaspoon of Epsom salt and 1/2 teaspoon of water in the other cup and dissolve that solution. It’s okay if all the Epsom salt didn’t dissolve.
  4. Pour the solution into the cup of glue. Stir.
  5. Do you notice a change in the solution? Grab the glob you’ve made and pile it on your paper towel-covered work surface. 
  6. Fold the towels over the glob and gently press the extra water out of it. Now discard the paper towels.
  7. Store your blob in a resealable plastic Ziploc bag. (Never pour a polymer concoction down the drain. If you need to discard it, put it in the trash).

WHAT HAPPENS: You’ve made a blob that you can bend, twist, squeeze, smoosh, roll, and bounce.

WHY IT WORKS: Glue remains a compound while making things stick together because it contains polyvinyl alcohol. That acts as a binder, keeping the glue semi-liquid and less likely to dry out. This makes glue perfect for making a polymer. The glue cross-links with the dissolved Epsom salt to create strong, flexible chains of molecules – which are a characteristic of polymers. Roll them into a ball and they bounce!

Super Starch Slime to the Rescue!!!

WHAT YOU NEED:

  • 1/4 cup of water
  • 1/4 cup of white craft glue (like Elmer’s glue)
  • 1/4 cup of liquid starch (used for clothes)
  • Food coloring (optional)
  • Mixing bowl
  • Mixing spoon

WHAT TO DO:

  1. Pour all of the the glue into the mixing bowl.
  2. Pour all of the water to the mixing bowl with the glue.
  3. Stir the glue and water together.
  4. Add your food color now – about 6 drops should do it.
  5. Now add the liquid starch and stir it in.
  6. It should be nice and blobby by now. As you play with your slimy concoction, it will become more stretchy and easier to hold.
  7. Explore your slimy creation and store it in a zip bag when you are not using it.

HOW IT WORKS:

The glue is a liquid polymer. This means that the tiny molecules in the glue are in strands like a chain. When you add the liquid starch, the strands of the polymer glue hold together, giving it its slimy feel. The starch acts as a cross-linker that links all the polymer strands together.

The reason the starch acts is a cross-linker is because it contains Borax (sodium tetraborate) in the ingredients. The borate ions in the borax link the polymer strands in the glue. (To learn more about cross-linking, visit “The Best Slime” page in the “Slime” menu).

Make it an experiment: 

The project above is a DEMONSTRATION. To make it a true experiment, you can try to answer these questions:

1. Does changing the amount of water or glue change the feel of the slime?

2. Do different glues make better slime?

3. How does changing the amount of each ingredient change how the slime turns out?

4. What happens to slime if it is stored out of a bag compared to in a bag?

Best Fake Blood Recipe

WHAT YOU NEED: 1 1/2 cups Karo Light Corn Syrup, 1/2 cup Rose’s Grenadine, bottle of red food coloring, clean and empty glass jar, spoon.

WHAT TO DO: Mix the corn syrup, grenadine, and food coloring in the jar to produce a nice, deep blood red. Stir well.

WHAT HAPPENS: You’ve made a fairly realistic prop blood for stage or screen.

WHY IT WORKS: The grenadine improves the flow of the corn syrup “blood” and lets it soak more realistically into clothing and other fabric.

How to Grow Crystal Needles in the Fridge

epsom crystals

This is what your crystals should look like.

Grow a cupful of Epsom salt crystal needles in your refrigerator. It’s quick, easy, and safe.

Difficulty: Easy
Time Required: 3 hours
WHAT YOU NEED:
  • cup or small bowl
  • epsom salt
  • hot tap water

WHAT TO DO:

  1. In a cup or small, deep bowl, mix 1/2 cup Epsom salt (magnesium sulfate) with 1/2 cup hot tap water (hot as it will get from the faucet).
  2. Stir about a minute to dissolve the Epsom salt. There will still be some undissolved crystals at the bottom.
  3. Place the cup in the refrigerator. The bowl will fill with needle-like crystals within three hours.

TIPS:

  1. Don’t use boiling water to prepare your solution. You will still get crystals, but they will be more threadlike and less interesting. The temperature of the water helps control the concentration of the solution.
  2. If you like, you can place a small object at the bottom of the cup to make it easier to remove your crystals, such as a quarter or plastic bottle cap. Otherwise, carefully scoop the crystal needles from the solution if you wish to examine them or save them.

WHAT’S GOING ON?

Solubility (the amount of something that will dissolve) is tied to temperature. The hotter the water is, the better it is at dissolving the Epsom salt. If you had a way to see the atoms along the edge of the crystals, you would notice that some of magnesium sulfate (Epsom salt) was constantly leaving the crystal to dissolve in the water, while other bits of magnesium sulfate were constantly leaving the water to join the crystal. If everything balances, then the crystals stay the same size.

On the other hand, if the water is hot, the extra energy lets more of the salt leave, throwing off the balance. That means that the solid Epsom salt will dissolve, until it reaches a new balance. At that point, the salt stops dissolving.

When you put the cup in the refrigerator, heat energy from the cup moves to the surrounding area. With less heat energy in the water, the balance shifts again. Now you have more Epsom salt joining the crystals, so the crystals grow. This will continue until things reach a new balance. At that point, the crystals stop growing.

If you want to experiment further, you can continue to play with that balance point. Once your crystals have grown, pour off the water. In another cup, mix another batch of hot water and Epsom salt. This time, wait until the water cools almost to room temperature, and then carefully pour it into the cup with the crystals from your first experiment. This time, do not stir! Put it in the refrigerator.

If you get the balance right, then your original crystals will not redissolve completely. As the solution cools, more magnesium sulfate will be added to the original crystals, causing them to grow larger. You can try repeating this several times. If your balance is off, and the crystals dissolve, then just heat the water again, and start over. When you are done, you can let the crystals dry and put them on your shelf. If they get broken or dusty, just dissolve them, and grow them again.

Salt and Vinegar Crystals

salt and vinegar crystals

You should be able to grow beautiful, colorful crystals like the ones in this picture.

Salt and vinegar crystals are easy-to-grow, non-toxic crystals that you can grow in a rainbow of colors. This crystal growing project is especially good for kids or beginners looking for quick and easy crystals.

WHAT YOU NEED:

  • 1 cup hot water
  • 1/4 cup salt (sodium chloride)
  • 2 teaspoons vinegar (dilute acetic acid)
  • food coloring (optional)
  • piece of sponge
  • shallow dish

WHAT TO DO:

  1. Stir together the water, salt, and vinegar. Boiling water works best, but very hot water is okay.
  2. Place the piece of sponge on the shallow dish. Pour the mixture over the sponge so that it soaks up the liquid and just covers the bottom of the dish.
  3. If you want colored crystals, you can dot the sponge with food coloring.
  4. Save the rest of the crystal growing solution.
  5.  Set the dish in a sunny window or other warm area with good air circulation. You will see crystal growth overnight or within a day. Add more crystal growing solution to replace the liquid that evaporates.
  6. Continue growing your crystals as long as you like. The project is non-toxic so when you are done you can either save your crystals or throw them away. You can dump leftover crystal solution down the drain and wash the dish as usual.

HOW IT WORKS: Salt dissolves better in hot water than cold water, so as the solution cools the salt wants to come out of solution and crystallize. When you pour the solution over the sponge, this causes the liquid to evaporate. This further concentrates the salt so that it will crystallize. The salt crystals will start to form on undissolved salt or on the sponge. Once the crystals start forming, they grow fairly rapidly.

Diaper Science

Have you ever changed a diaper and noticed those tiny crystals on the baby’s skin? Those tiny crystals are found inside the lining of the diaper and are made out of a non-toxic, moisture-absorbing polymer. Basically, it absorbs the baby’s pee so it doesn’t get all over the place.

WHAT YOU NEED:

  • Disposable diapers (several brands) – I suggest a cheap brand for a demonstration
  • Pure sodium polyacrylate powder (Optional. Can be found online or at a chemical supply store. Sometimes labeled as Insta-Sno or PolySnow)
  • Radish seeds (optional)
  • Ziploc bag
  • Scissors
  • 8-ounce plastic cup
  • Distilled water
  • Newspaper
  • Salt
  • Spoon
  1. Place a brand new diaper on a piece of newspaper. Carefully cut through the inside lining and remove all the cotton-like material. Put all this material into a clean Ziploc bag.
  2. Pick up any of powder that may have spilled onto the paper and put it into the bag with the stuffing. Blow a little air into the bag to make it puff up, then seal it.
  3. Shake the bag for a while to remove the powdery polymer from the cotton-like material. Notice how much, or how little, powder falls to the bottom of the bag.
  4. Carefully remove the stuffing and check out the dry powder you extracted.
  5. Pour this powder into a plastic cup and fill the cup with distilled water. Stir it around with your finger until the mixture begins to thicken.

What to do with your diaper gel:

  1. Try holding the cup upside down over a protected surface. Does the gel fall out?
  2. With the pure sodium polyacrylate powder you bought online or at a chemical supply store, you can perform a little magic trick! Put about a teaspoon of the powder in an OPAQUE cup ahead of time. Also add a little water to the powder so it won’t fall out. Next, get two other cups and place ALL the cups upside down. Now you’re ready for the trick. Gather your audience and make sure they see that all the cups are upside down. Then, turn them all right side up again. Pour about a half cup of water to the sodium polyacrylate and shift the cups around to try and “confuse” the audience. Now ask them which cup the water is in. Flip all the cups upside down and all the water will have “magically” disappeared!
  3. Submerge a fresh diaper in water for a minute or two. Take out the diaper and cut it open. What do you see?
  4. Try adding a couple teaspoons of salt to the diaper gel. What happens?
  5. Make some fresh diaper gel in a clear cup and add some radish seeds. Observe what happens over a period of several weeks.
  6. Store your diaper gel in a Ziploc bag.

How does it work?

The secret water-absorbing chemical in a diaper is a super-absorbent polymer called sodium polyacrylate. A polymer is simply a long chain of repeating molecules. If the prefix “poly” means many, then a polymer is a large molecule made up of many smaller units, called monomers, which are joined together. Some polymers are made up of millions of monomers.

Super-absorbent polymers expand tremendously when they come in contact with water because water is drawn into and held by the molecules of the polymer. They act like giant sponges. Some can soak up as much as 800 times their weight in water! That would be one wet baby!

The cotton-like fibers you removed from the diaper help to spread out both the polymer and the, uh, “water” so that baby doesn’t have to sit on a gooey lump of water-filled gel. It’s easy to see that even a little bit of powder will hold a huge quantity of water, but it does have its limits. At some point, baby will certainly let you know that the gel is full and it’s time for new undies!

In spite of their usefulness, these diapers can be a problem. If you’ve ever observed a baby in diapers splashing in a wading pool, you know that even one diaper can absorb lots and lots of water. Most public pools won’t allow them to be worn in the water because huge globs of gooey gel can leak out and make a mess of the filter system. Also, some folks used to throw them away in toilets – not a good idea unless you’re a plumber. For the most part, however, these diapers are a great invention and make for dry, happy babies.

Science Fair Connection:

A good science fair project changes something, creates a new experiment, and compares the results.

  • Change the brand of diaper and, using the steps listed above, test it to see just how much water it will absorb. Compare your results to the absorbency of the first diaper you tested.

The brand of diaper is the variable in this experiment. Be sure to use the same size of diaper even though you are using different brands. If you test a large Pampers diaper against a newborn-sized Huggies diaper, your results will not be reliable. Everything needs to stay the same except for the brand of diaper. You’ll find out extremely quickly if you get what you pay for or if there really isn’t a difference between the brands. Document your discoveries and share them at the science fair. Many moms with young children will thank you for your research!