A chemical reactionoccurs when substances are mixed together and are changed. Sometimes substances mix together and not much happens, at other times the results are pretty dramatic. Today we will look at a turbo charged chemical reaction. We will mix two substances together and add a catalyst, something to make the reaction happen faster.
What You Need:
Plastic Soda Bottle
Pour a cup of hydrogen peroxide in the liter soda bottle. Add a few drops of food coloring and a few drops of dish soap. In a separate bowl mix 1 teaspoon of yeast with two tablespoons of hot (not boiling – just use hot water from the faucet) water. Use the funnel to pour the yeast mixture into the mottle. Stand back!!
HINT: Do this one OUTSIDE!
HINT #2 If you want your geyser to spew more, use a plastic soda bottle that is smaller than a liter - a bottle that is smaller will have more foam shoot out of it.
Hydrogen peroxide has a lot of bubbles in it. If you let it sit long enough it will go “flat” – just like soda if you let it sit, the bubbles pop and eventually no carbination is left. When you add the yeast to the hydrogen peroxide the yeast makes this “going flat” happen super fast. The yeast breaks the hydrogen peroxide down into oxygen and water – a chemical reaction. The oxygen combines with the dish soap to make a whole lot of bubbles. In this experiment yeast is a catalyst. A catalyst speeds up a chemical reaction. Once the chemical reaction is over touch the foam – how does it feel? You might notice that the foam is a little bit warm. This chemical reaction is an exothermic one, that means that the chemical reaction produced a little heat.
Here are some websites and books that will give you more chemical reaction experiments to try:
Chemical Reaction – When a substances or substances is changed into a new substance. Exothermic – A chemical reaction that produces heat. Catalyst – Something that makes a chemical reaction happen faster.
A pendulum is a weight hanging from a fixed point. A yo-yo on a string can be a pendulum if you have ahold of the string and hold it in one place while the yo-yo hangs down freely. Pendulums are also associated with clocks or hypnotists, who swing an object back and forth from a fixed point. On a swing, YOU are a pendulum. Pendulums are affected by laws of motion. When a pendulum swings it has momentum. In this video, Bill Nye the Science Guy demonstrates momentum:
Things You Need:
String 3 feet long
2 Strings 2 feet long
This experiment will show you something surprising about how momentum works. Set two chairs back to back about 3 feet apart. Tie a piece of string to the back of one chair and toe the other end to the back of the other chair. The string should not have a lot of slack in it. Tie a 1 foot long piece of string to the piece of string suspended between the two chairs about 18 inches from one of the chair backs. Now tie the other 1 foot piece of string to the suspended string about 18 inches from the OTHER chair back. When you are done, the two pieces of string should be a about 1 foot apart. Now tie a mug to the end of each dangling piece of string. Pull back on one mug and let go, letting it swing back and forth until it stops. Does it stop? What does the other mug do? When you release the first mug, momentum keeps the mug swinging back and forth. The mug will swing until friction in the air and friction from the string knot rubbing on the handle slows it down.
The weird thing is that when the first mug slows down…the second mug will START swinging, even though you never touched it! Some energy from the first mug travels along the string and makes the OTHER mug start swinging. Even though the momentum of the swinging mugs is slowed down by friction, some of the energy is transferred to the string, which carries it to the second mug.
Science Project Idea: Replace the mugs in this experiment with matching objects of different weight. Try two matching plastic mugs. How much momentum do the plastic mugs have? Does the momentum from a plastic mug have enough energy to pass through the string to the second plastic mug? Try hanging two metal forks from the string. Now try two plastic forks. Which kinds of objects have enough momentum to transfer energy to the second object without even touching it?
Here are some books and websites that will help you explore momentum and understand why heavier objects create more momentum:
The surface layer of liquids has a thin elastic “skin” called surface tension. You can see surface tension at work when you see a drop of water – it creates a little “bead” of water, like a little dome. Surface tension is what makes the dome shape – the water doesn’t flatten out. See the drops of water on that leaf? Water is made up of two kinds of atoms, hydrogen and oxygen. The name for the water molecule is H20. The water molecule has 2 hydrogen atoms and 1 oxygen atom. Water molecules are attracted to each other because hydrogen atoms and oxygen atoms are attracted to each other and hug close together really tight. They hug so close together they don’t want to touch other molecules around them. In the picture, you can see that the water drops have formed into balls so that they are touching the smallest amount of leaf possible.
Try this to see surface tension at work:
What You Need:
Fill the bowl with water. Sprinkle some pepper on top of the water – see how it just sits there on top of the water? The pepper is resting on that thin “skin” of surface tension. You can also try this with toothpicks – the toothpicks will also just sit on top of the water resting on the thin “skin” of surface tension.
No put a few drops of dish soap in the water with the pepper. What happens? Soap molecules are different than water molecules. Soap molecules DON’T stick together and they DON’T stick to the water molecule. One part of the soap molecule is attracted to water and the other part wants to push water away – that’s what makes the pepper, or the toothpicks, scatter. The soap breaks the surface tension that water has, it breaks those bonds between the water molecules.
Here are some books and websites to help you explore more about surface tension:
Vinegar is an acid. Eggshells are made of calcium carbonate. If you soak an egg in vinegar the eggshell will absorb the acid and break down, or dissolve. The calcium carbonate will become carbon dioxide gas, which will go into the air. What is left is the soft tissue that lined the inside of the eggshell.
Science Experiment Idea: Make three bouncing eggs. Soak one egg in water for 24 hours (1 day), one egg for 48 hours (2 days) and one egg for 36 hours (3 days). How do the eggs look when done soaking? How does each egg behave when you try to bounce it? Hint: BOUNCE OUTSIDE!
Here are some websites that will help you understands acids and how they behave:
Acid – A chemical that is often sour tasting and corrosive. It dissolves some things. Dissolve – When a solid comes apart and spreads out into a liquid…like kool aid in water. Calcium - One of the most common minerals found in animals bodies. It makes up bones, teeth, and eggshells. Absorb – To soak up…like a sponge in water.