CHAPTER 21

Experiments Around the House

There are some science experiments that are good to do with your child, not because they reinforce the skills of a particular branch of science, but because they show your child that she can use science to influence or change ordinary household objects. The experiments in this chapter range from one that teaches about the importance of dental hygiene to another that demonstrates the power of combining common household ingredients in a sandwich bag. What they all have in common is that they use stuff you already have around your house.

Naked Egg

The Naked Egg experiment is good experiment to help show your child the effect that acid can have on calcium carbonate, a substance found in eggshells, bone, and your child’s teeth.

Putting an egg in an acid solution isn’t quite the same as your child not brushing her teeth well, but the chemical reaction is similar enough that the Naked Egg experiment stands as a precautionary tale. Not only that, but when you’re done with the experiment, your child will be able to see what an egg looks like naked. That’s not something that happens every day!

Tooth decay is caused by the acid created by the interaction of the bacteria in your mouth and the sugars and carbohydrates that you eat. It’s not the same as immersing your teeth in vinegar, but it has the same effect. Luckily, you can brush your teeth to stave off tooth decay!

This experiment will take between 48 and 72 hours.

Skills Being Practiced

What You Need

Create a Hypothesis

  1. Ask your child to look at her teeth in the mirror, and then look at the egg. What do they have in common? Though she may answer that they are both white, it goes beyond that. Explain that an eggshell is made up of a substance known as calcium carbonate, and ask her if she’s ever heard of calcium. Remind her that she drinks milk because it contains calcium, and that it helps to make her teeth and bones strong.
  2. Now ask her to think about what might happen if she left that calcium-covered bone, tooth, or egg in an acidic solution overnight. Have her write down her hypothesis so she can compare it with what actually happens.

How to Play

  1. Find an out-of-the-way place, preferably on the kitchen counter, to set up your experiment. Ask your child to carefully take an egg out of the refrigerator and put it in the clear plastic cup. If your child drops the egg, that might actually be helpful to your experiment, as it can show her how fragile the egg is and what it contains inside the shell.
  2. Pour vinegar into the cup until the egg is completely immersed.
  3. Leave the egg overnight, and have your child check it in the morning. She may notice that there are bubbles on the eggshell or that the top of the liquid is covered in a foamy substance. Ask her to take a guess as to what the bubbles and foam are.
  4. Help your child remove the egg from the cup with a large spoon. Then pour the vinegar and foam out of the cup into the sink. Put the egg back in the cup, pour in new vinegar, and let the egg sit for another day or two.
  5. On day three of the Naked Egg experiment, remove the egg from the cup with a spoon and rinse it under a very gentle stream of water. Whatever eggshell is remaining will probably wash off during this process. Do not remove the egg with your hands or rub it when you rinse it off. Since the egg’s shell has almost completely dissolved, it is by now nothing more than a sort of egg water balloon that can burst in your hand with the slightest amount of pressure.
  6. Rinse out the plastic cup, and gently place the egg back inside. Have your child crouch down to “egg level” and aim a flashlight beam behind the egg. With only the membrane remaining, the egg should be somewhat translucent and take on a glow when the light goes through it.

Questions to Ask

What’s Going On

The vinegar you used is an acid known as acetic acid, but it also contains some water. The vinegar interacts with the calcium carbonate in the eggshell and creates a chemical reaction, the first sign of which is the bubbles you saw on the eggshell. Since the acid breaks the calcium carbonate apart into calcium and carbonate, the carbonate works with the water in the vinegar to create carbon dioxide gas—the bubbles that form on the egg.

The calcium component of the eggshell is suspended in the vinegar and creates the foamy substance in the liquid. The chemical reaction continues until all of the calcium carbonate is gone, leaving behind an egg without a shell.

Coloring Carnations

The Coloring Carnations experiment helps to explain why the water level in a vase of flowers drops, why houseplants need to be watered, and where all that water goes. By adding food coloring to the water, your child can follow the water’s movement as well as see the flowers “eating.” You will also end up with a beautiful rainbow bouquet to brighten up a room.

This experiment will take between 24 and 48 hours.

Skills Being Practiced

What You Need

Create a Hypothesis

  1. Ask your child if he has ever wondered what happens to the water in a vase of flowers, or why it has to be replaced every few days.
  2. Show him the white flowers and tell him you want to see how the flowers and the dropping water level are connected, and that in order to do that, you’re going to use colored water.
  3. Have him take a guess as to what will happen to the flowers if they are placed in colored water.

How to Play

  1. Fill each vase or water bottle about three-quarters full of water. (If there are labels on the water bottles, have your child peel them off before filling them.).
  2. Ask your child to add one color of food coloring to each bottle, or to mix drops of primary colors to make secondary colors in a bottle, like purple, green, and orange. Use enough food coloring to make the water very bright, about 15–20 drops per bottle.
  3. Use a pair of scissors to trim the flower stems, so they can fit in the bottle without tilting over the side. Fill a large bowl with water, and place all the flower stems in the bowl. One at a time, make a diagonal cut on the bottom of each stem while they are underwater. Cutting flower stems underwater helps with this activity, because it prevents the formation of air bubbles in the tubes at the base of the stem. Air bubbles can block the capillary action that draws water up the stem like a straw. A diagonal cut also aids capillary action, because it prevents the stem from sitting flat on the bottom of the vase, which makes it more difficult for the stem to take in water.
  4. Place each carnation in a separate vase or bottle of colored water, and have your child check on them every few hours. The effect of some of the brighter colors can sometimes be seen in as few as a couple of hours, but the most drastic effect will be seen within 24 hours.
  5. Leave the flowers overnight, and check them in the morning.

Observations

Once 24 hours have passed, the flowers should really be on their way to becoming very colorful. It’s time to start asking your child about what he has observed. Ask questions like:

What’s Going On

When plants and flowers are planted in pots or the ground, they get nutrients from the water they absorb from the soil. Cut flowers do not have roots, but are able to “drink” water through their stems in a process known as transpiration. As the leaves and petals of the plants lose water to evaporation, it creates a force called cohesion that essentially pulls other water molecules into the space the evaporated water vacated.

Water travels through small tubes in the stem, much like a liquid through a straw, though the force behind it is cohesion, not someone sucking on the flower! This traveling motion is known as capillary action. The water is then distributed to the parts of the flower that need water and nutrients, including the petals. Since you and your child have dyed these “nutrients” various colors, the color also is deposited in the petals.

EXTEND THE LEARNING

Not all of the capillaries in a flower stem deliver nutrients to every single one of the petals. You can demonstrate this by splitting one of the carnation’s stems in half from the bottom to the base of the flower. Place each half in different color water, and the flower will end up multicolored!

Bottle Balloon Blow-Up

If your child jumps for joy at the thought of blowing things up, she will really enjoy the Bottle Balloon Blow-Up experiments. Though her excitement may die down temporarily when she realizes the only thing getting blown up is the balloon, it will be quickly reignited when she realizes that she can blow up balloons using various forces, none of which include forcing air from her lungs into the balloon. These experiments work best with latex balloons. However, before you begin, make sure none of your participants have latex allergies.

Skills Being Practiced

Baking Soda Balloon Blow-Up Experiment

This experiment demonstrates the power of the chemical reaction created by combining baking soda and vinegar. It’s powerful enough to blow up a balloon!

What You Need

Create a Hypothesis

Ask your child to predict what will happen when you combine baking soda and vinegar in a bottle. If she’s ever seen a science-fair volcano, it’s a good time to remind her that these are the same ingredients used in the volcano. Ask her to predict what will happen if you combine the same ingredients, but cover the top of the bottle with a balloon.

How to Play

  1. Fill a clean, empty water bottle about one-third full with vinegar.
  2. Place a funnel in the neck of the balloon, and hold onto it as your child pours in enough baking soda to fill the balloon about halfway.
  3. Slip the funnel out of the neck of the balloon. Ask your child to hold the portion of the balloon with the baking soda in it to the side and downward as you stretch the neck of the balloon up over the neck of the bottle, being careful to not let any of the baking soda slip into the bottle. Make sure it is secure.
  4. Help your child slowly lift the balloon over the bottle, and let the baking soda pour inside.
  5. Ask your child to move aside. Have her listen and watch the bottle carefully. As you begin to hear the fizzing and crackling noise the baking soda and vinegar solution makes, hold tight to the neck of the balloon.
  6. Watch as the balloon begins to inflate!

What’s Going On

When the baking soda and vinegar are combined, the acetic acid in the vinegar breaks down the chemical composition of the baking soda (calcium carbonate). The carbon combines with some of the oxygen in the bottle to create carbon dioxide gas, which then rises and inflates the balloon.

Balloon in a Bottle Experiment

This experiment demonstrates that changing the air pressure inside a bottle with a little heat can make enough of a change to completely change the position of a balloon on the top of the bottle. This experiment requires precise timing and moves very quickly, so it’s more suited for your child to be an observer, not an active participant. In order to help him feel more involved, you can designate him as the “official experiment recorder.” Give him your cell phone or video camera to film the experiment as you do it.

What You Need

How to Play

  1. Place the neck of the balloon over the neck of a faucet. Turn the water on low and fill the balloon with just enough water so that it is a little too big to fit through the mouth of the jar. Tie off the neck of the balloon.
  2. Grasp the piece of paper towel or tissue with a pair of tongs, and light it on fire. Drop it into the jar.
  3. Very quickly, put the water balloon on the top of the jar, and watch what happens. The balloon will dance, and then be sucked right into the jar.

What’s Going On

At the beginning of the experiment, the air pressure inside and outside the jar is the same, but as the paper burns, it heats up the air inside the jar. The heated air expands, taking up more room, but the balloon is impeding the air’s escape route. As the heated air pushes around the balloon to get out of the jar, the balloon “dances” out of the way.

Once the fire goes out, the air in the jar cools, but since the water balloon is blocking the opening, no new air can get into the jar. That means the air pressure in the jar is lower than that of the pressure outside the jar. The outside air pressure exerts force on the balloon, pushing it into the jar.

Film Canister Rockets

So far in this book, your child has seen how the chemical reaction between calcium carbonate and vinegar can remove an eggshell, and how it can be used to blow up a balloon. Now she can see how that reaction can be harnessed to create a flying object. With a little open space and some caution, your child can send a film canister flying through the air simply with the power of a little fizzy reaction. However, with digital cameras taking over the market, it is becoming harder and harder to find film canisters (you can try photo shops or stores that do one-hour processing, but not many people use 35mm film these days). If you are unable to locate film canisters, a clean, empty glue stick container or a small, empty candy tube with a snap cover will also work for making rockets.

The tissue is not a necessary component in the experiment, but it helps to delay the chemical reaction enough to let you have some time to get out of the way. Experimenting with different types of paper and the amounts of baking soda and vinegar can help make the rocket fly higher, faster, or even be timed to a countdown.

Skills Being Practiced

What You Need

(not all materials are needed for all experiments):

How to Make Baking Soda and Vinegar Rockets

  1. Give your child a film canister (or other small tubular container with a cover), markers, and card stock. Have her draw and decorate a small rocket on the card stock.
  2. Ask her to cut the rocket out and set it aside. Give her another piece of card stock to roll into a tube. Tape this tube around the container, making sure the cover of the container is accessible at the bottom. Glue the rocket to the front of the paper tube to make the whole apparatus look more like a real rocket.
  3. If you have used a candy container, cut the hinge on the lid so it can be completely removed from the canister.
  4. Move outside to a clear, unobstructed area.
  5. Open the container, and fill it one-quarter of the way with vinegar.
  6. Fold 1 teaspoon of baking soda into a small piece of tissue. Get ready to act quickly and stand back.
  7. Place the folded tissue in the container, snap it shut, and stand it up (lid down) on the ground. Step away from the rocket.
  8. As the tissue dissolves in the vinegar, the rocket should fly into the air.

How to Make Antacid Rockets

  1. Clean out the rocket from the previous experiment.
  2. Remove the lid, and drop an antacid tablet into the body of the rocket. Though you can use generic brand antacids, Alka-Seltzer tablets just seem to work better than the alternative brands.
  3. Add a teaspoon of water to the container, snap the lid on, and place the rocket on the ground, lid down.
  4. Watch what happens as the water works to dissolve the tablet.

What’s Going On

Both the baking soda and vinegar mixture and the water and antacid combination work together to create a chemical reaction that releases carbon dioxide gas. As the gas fills the container, the air pressure inside builds to a point where it is too great to be contained. At that point, the lid pops off the container and the rocket zooms up into the air.

EXTEND THE LEARNING

Have your child compare the two rockets. Which worked better? Does changing the amount of baking soda or vinegar make a difference? What happens if she substitutes soda for water in the antacid rocket?

Incredible Exploding Sandwich Bag

If a baking soda rocket wasn’t enough of an explosion for your child, then this experiment is bound to be more his style. Using the same acid-base reaction that makes quick bread rise when you cook, this experiment shows that sometimes, combining common household products can be explosive without being dangerous. However, this experiment is definitely messy! Take your materials outside, or choose a place to “explode” your sandwich bag that can be cleaned up easily. Try the kitchen sink, the bathtub, or even a big plastic toy bin.

Skills Being Practiced

What You Need

How to Play

  1. Enlist your child’s help in locating a zip-top bag that doesn’t leak. Though you may think that a bag that comes right out of the box would be leak free, sometimes the seams let water through, and using a watertight bag is crucial to the experiment. To check for leaks, fill each sandwich bag about half full with water, close it, turn it upside down, and shake it around. Once you find a few nonleaky bags, empty them and set them aside.
  2. Ask your child to measure a 5″ × 5″ square of paper towel, and use a pencil to mark it off. Check his measurements and then ask him to cut out the square.
  3. Lay the paper towel square down on a flat surface. Measure 1½ tablespoons of baking soda, and place it in the middle of the paper towel.
  4. Help your child fold the paper towel into a small packet. Begin by folding the top third over the mound of baking soda, then folding the bottom third up over it as well. Then fold each side into the middle of the rectangle, creating a small square. This is your timed-release “explosive” packet. Set it aside.
  5. Have your child measure ½ cup of vinegar. Hold open a sandwich bag while he pours the vinegar inside. Continue holding the bag while he measures and pours in ¼ cup of warm water.
  6. This next step requires some fast moving on the part of both you and your child. Zip the sandwich bag about halfway closed. Stuff your timed-release packet inside while you very quickly zip up the rest of the bag.
  7. Make sure the bag is secure, then shake it a little bit. Place it on the ground or in the designated safe zone, move back, and watch as the bag expands and explodes!

Questions to Ask

What’s Going On

Once the paper towel dissolves, the baking soda is mixed with the vinegar-water solution. Since vinegar is an acid and baking soda is a base, it creates a chemical reaction called an acid-base reaction. The acid-base reaction makes carbon dioxide gas, which needs more space than the sandwich bag can accommodate. It keeps filling the bag until there isn’t any more room. The gas then pops out the seams and tops of the bag with a loud (and very visible) explosion.