Experiments

ELEPHANT TOOTHPASTE

Elephant toothpaste

The Experiment

Hydrogen peroxide is added to soap.  With a catalyst present, something that speeds up a chemical reaction, tons of bubbles are formed.  The result is a foamy mess that looks like Elephant Toothpaste.

What’s Happening?

Hydrogen peroxide is made of 2 hydrogen atoms and 2 oxygen atoms and is written as H2O2.  With the aid of a catalyst, the hydrogen peroxide easily breaks down making water (H2O) and oxygen gas (O2).  In the presence of soap, the final product will be soap, water, and a fun foamy mess.  Make sure you do this in a container so that a mess is not made.

Required Materials

  • 3% Hydrogen peroxide
  • Yeast (catalyst)
  • Food coloring (to make look extra cool!!)
  • Dish Soap
  • Empty soda container or tall skinny bottle
  • Warm water

How to…..

  • Mix ½ cup of hydrogen peroxide with ¼ cup of dish soap
  • Add the mixture to the empty soda bottle
  • Mix one packet of active yeast to warm water and let sit for a few minutes
  • Pour into the mixture of hydrogen peroxide and soap using a funnel
  • Watch the reaction happen!!!!

 

POLYMER BOUNCY BALLS

The ExperimentBouncy Balls

Balls have been toys practically forever, but the bouncing ball is a more recent innovation. Bouncing balls were originally made of natural rubber, though now bouncing balls can be made of plastics and other polymers or even treated leather. You can use chemistry to make your own bouncing ball. Once you understand the basic technique, you can alter the recipe for the ball to see how the chemical composition affects the bounciness of the ball, as well as other characteristics.

What’s Happening??

The bouncing ball in this activity is made from a polymer. Polymers are molecules made up of repeating chemical units. In a way, they are like long spaghetti strands. Glue contains the polymer polyvinyl acetate (PVAc), which cross-links to itself when reacted with borax. Basically, borax acts as a linker to bring together the spaghetti strands into a network.

PVAc - BoraxPolymer Crosslinking

Required Materials

  • borax (found in the laundry section of the store)
  • white glue (e.g., Elmer’s glue – makes an opaque ball) or blue or clear school glue (makes a translucent ball, looks nicer)
  • to provide color (optional) use food coloring or highlighter juice (break a highlighter and extract the ink by submerging it into a little bit of water.
  • measuring spoons
  • spoon or craft stick to stir the mixture
  • Marker or sharpie
  • 2 small plastic cups or other containers for mixing
  • zip-lock plastic baggie (to store your ball or gue)

How to…..

  1. Label one cup ‘Borax Solution’ and the other cup ‘Ball Mixture’.
  2. Pour 2 tablespoons warm water and 1/2 teaspoon borax powder into the cup labeled ‘Borax Solution’. Stir the mixture to dissolve the borax.
  3. Pour 1 tablespoon of glue into the cup labeled ‘Ball Mixture’. Add a little bit of color (food coloring or highlighter juice)
  4. Mix the borax solution and the glue mixture. Do not stir. Allow the ingredients to interact on their own for 10-15 seconds and then stir them together to fully mix. Once the mixture becomes impossible to stir, take it out of the cup and start molding the ball with your hands.
  5. The ball will start out sticky and messy, but will solidify as you knead it.
  6. Once the ball is less sticky, go ahead and bounce it!
  7. You can store your plastic ball in a sealed ziploc bag when you are finished playing with it.
  8. Don’t eat the materials used to make the ball or the ball itself. Wash your work area, utensils, and hands when you have completed this activity.
  9. Now you can experiment with the procedure and see what happens!!! For example, what if you add more or less borax? What happens if you dilute the glue with water before reacting with borax? Can you use other colors?

Note: if you used yellow highlighter juice to provide color, you now have a fluorescent ball. If you shine it with a black lamp you will see that your ball glows (fluoresces) with green color. See our handout on fluorescence below!

 

FLUORESCENCE

The Experiment

Fluorescence is the ability of certain substances to take light of one color and emit light of a different color. You can explore the concept of fluorescence at home by illuminating objects with a high-energy lamp and observing for light emission.

What’s Happening??

Substances that fluoresce absorb light of high energy (left side of the light spectrum in the image below) and emit light of a lower energy (to the right in the light spectrum). Fluorescence is a specific property of certain substances. Some animals can fluoresce too! See the images of a scorpion and jellyfish below. In this experiment you will use a black lamp which emits ultraviolet light (left-most on the spectrum below) and observe for light emitted from your sample in the visible range (blue to red).

Note that fluorescence is used in science for a lot of applications because it allows us to clearly see what we’re looking for. For example, fluorescence can be used to label different parts of cells (nucleus, membrane, etc.) with different colors so that they can be clearly observed by microscopy (see image on the left bottom corner below). Also, fluorescence is used for cancer imaging (see image on the right bottom corner below).

FLUORESCENCE HANDOUT

Required Materials

  • Fluorescent substances such as a yellow highlighter, highlighter juice (obtained by submerging the inside ink felt of the highlighter in water), some types of sneaker shoes, and/or some types of white t-shirts or socks.
  • Black lamp (ultraviolet lamp)

How to…..

  1. Shine the objects that you want to investigate with the black lamp
  2. Observe for emission of light
  3. Note: if you used yellow highlighter juice to provide to bouncy balls in the previous experiment, you now have a fluorescent ball. If you shine it with a black lamp you will see that your ball glows (fluoresces) with green color.

 

 NEUTRALIZATION REACTION

The ExperimentNeutralization

In this experiment we will be allowing a reaction to occur and the byproducts will be used in inflate a balloon!!  This is kid friendly and can be performed using household products.

What’s Happening??

During the reaction given below, Sodium Carbonate (Baking Soda) and Acetic Acid (Vinegar) are used to neutralize each other.  Baking soda is a base and vinegar is an acid.  But together they are neutral.  During this reaction carbon dioxide and water are formed.  Carbon dioxide is a gas and is used to inflate the balloon.  All by-products are completely safe.

NaHCO3 + CH3COOH → NaC2H3O2 + H2O + CO2

Required Materials

  • Empty water bottle
  • Vinegar
  • Baking soda
  • Large balloons

How to…..

  1. Fill an empty water bottle 1/3 of the way full with vinegar
  2. Fill a balloon about ½ the way full with baking soda
  3. Put the balloon on top of the water bottle
  4. Empty the contents of the balloon into the water bottle
  5. Hold onto the balloon as it expands

You can add food coloring for effect.  Another fun thing to do is leave the balloon off and pour the baking soda into the water bottle.  If you try this one, make sure to put something underneath to catch the liquid as it comes out of the top of the bottle.

DANCING OOBLECK

The ExperimentDancing Oobleck

In this experiment cornstarch is mixed with water to make oobleck.  You will see that the properties of this material are unique.  The material can behave as both a liquid and a solid. This can be tested by jabbing at the material with your fingers or punching the surface.  However, if you instead slowly put your fingers into the material, it will flow like a liquid.  If placed on an old speaker the material will begin to make a fun to watch dance!!

What’s Happening??

All fluids have a property known as viscosity that describes how the fluid flows – commonly thought of as how thick or thin a fluid is. For instance, honey is much more viscous than water. When a fluid’s viscosity is constant it is referred to as a Newtonian fluid.  Oobleck is an example of a fluid whose viscosity is not constant, it changes depending on the stress or forces applied to it. If you poke it with your finger and apply a large force, it becomes very viscous and stays in place. If you gently pour it, applying little force, it will flow like water. This kind of fluid is called a dilatant material or a shear thickening fluid. It becomes more viscous when agitated or compressed.

Another non-Newtonian liquid is ketchup. Ketchup behaves in just the opposite way from oobleck. It becomes less viscous when agitated. Liquids like this are called thixotropic. If you leave a bottle of Ketchup on a shelf, it becomes thicker or more viscous. Nearly everyone has experienced this while trying to pour the liquid from a new bottle – it refuses to move. If you shake the bottle or stir it up it becomes less viscous and pours easily.

The most generally accepted explanation for the behavior of Oobleck is offered by Cary Sneider in “Oobleck: What do Scientists Say?”. When sitting still the granules of starch are surrounded by water. The surface tension of the water keeps it from completely flowing out of the spaces between the granules. The cushion of water provides quite a bit of lubrication and allows the granules to move freely. But, if the movement is abrupt, the water is squeezed out from between the granules and the friction between them increases rather dramatically.

Required Materials

  • Corn starch
  • Water
  • Bowl and mixing spoon
  • Old cookie sheet
  • Food coloring (optional)
  • Old speaker to provide vibrational energy to the material

How to…..

Simply mix 2 cups of corn starch with 1 cup of water in a bowl.  After mixing you can add food coloring as desired for enhanced effect.  Try playing with the oobleck to experience the material’s unique properties.  Then pour the oobleck over a cookie sheet.   Place the cookie sheet over an old speaker and watch the oobleck dance.   This is a fun experiment that can be done at home.  However, the experiment can get quite MESSY so be sure perform in the kitchen.  Also, dilute the oobleck before pouring down the sink with the addition of excess water for disposal.  The material can also be discarded in the trashcan.

 

EXPLORING DENSITY

The ExperimentDensity

In this experiment we will be the property of density to stack liquids!!

What’s Happening??

The same amount of two different liquids will have different weights because they have different masses. The liquids that weigh more (have a higher density) will sink below the liquids that weigh less (have a lower density).  Density is basically how much “stuff” is smashed into a particular area… or a comparison between an object’s mass and volume. Remember the all-important equation: Density = Mass divided by Volume. Based on this equation, if the weight (or mass) of something increases but the volume stays the same, the density has to go up. Likewise, if the mass decreases but the volume stays the same, the density has to go down. Lighter liquids (like water or rubbing alcohol) are less dense than heavy liquids (like honey or Karo syrup) and so float on top of the more dense layers.

Liquid

Density (g/mL)

Rubbing alcohol

0.79

Lamp oil

0.80

Baby oil

0.83

Vegetable oil

0.92

Ice cube

0.92

Water

1.00

Milk

1.03

Dawn dish soap

1.06

Light corn syrup

1.33

Maple syrup

1.37

Honey

1.42

Required Materials

  • Light Karo syrup
  • Water
  • Vegetable oil
  • Dawn dish soap (blue)
  • Rubbing alcohol
  • Baby oil
  • Honey
  • Tall clear container
  • Food Coloring or True Color Coloring Tablets
  • Food baster
  • 9 oz portion cups

How to…..

  1. Pour the different liquids into 9oz portion cups and add food coloring for effect.  Light Karo syrup is easier to color than dark syrup.  Vegetable oil and honey cannot be colored.
  2. Pour the liquids SLOWLY, one at a time, into the clear container in the following order:  Honey, Karo syrup, dish soap, water, vegetable oil, rubbing alcohol, and baby oil.
  3. As you pour, the liquids will stay separated and form layers.


BERNOULLI EFFECT

The ExperimentBernoulli

In this experiment we create a situation where a ping pong ball can hang suspended in air.

What’s Happening??

This phenomenon is known as the Bernoulli Effect.  As you blow the straw, fast air surrounds the ping pong ball.  The fast air creates a pocket of low pressure in which the ball cannot escape.  The air around the fast air is of higher pressure, further trapping the ball.

Required Materials

  • Ping pong balls
  • Straw
  • Empty water/soda bottle

How to…..

  1. Make a funnel out of an empty water or soda bottle.  Cut the bottle in half.  You want to keep the coned portion at the top of the bottle.
  2. Take the lid off of the bottle.  Make a hole in lid large enough for a straw to fit into.
  3. Replace the lid on the funnel (bottle)
  4. Put the ping pong ball into the funnel
  5. With a straw blow air into the funnel

HOME-MADE LAVA LAMP

Materials:Lava Lamp

  • Water
  • Clear bottle
  • Alka-Seltzer
  • Food coloring
  • Vegetable oil
  • Optional: Flash light

Procedure

  1. Pour water into the plastic bottle until it is a quarter full.
  2. Slowly pour vegetable oil into the bottle of water to help keep the layers separately.
  3.  Add in 10 drops of food coloring, and observe the color change in the water.
  4. Drop an Alka-Seltzer into the bottle and observe the reaction.
  5. This may be done in a dark room with a flashlight to enhance the “lava-like” effects.
  6. Reaction can be repeated by dropping more Alka-Seltzer into the bottle.

What’s Happening?

It can first be seen that water and oil do not mix by the separation of the two layers. The two layers are not “miscible” (they don’t mix) and the water will settle to the bottom due to it having a lower density. The solubility of the food coloring can then be observed because it will only mix with the layer of water and will not affect the color of the oil.

The second part of the reaction can be observed when the Alka-Seltzer  is mixed . The Alka-Seltzer will only react with the water to form bubbles of Carbon Dioxide. These bubbles will attach to the colored water and be pushed up through the oil. After the carbon dioxide bubbles pop, the water will sink back to the bottom of the bottle.