Even though air seems like nothing, it really is something. Gases like air, even though they are not visible to our eyes, are made up of molecules just like solid objects. These molecules are pulled toward the earth by gravity.
Earth is surrounded by a layer of air that is heavy. That layer of air exerts pressure on the surface of the earth, a lot of pressure. Our bodies are used to it so it doesn’t bother us. In fact, we are so used to it that what bothers us is when the air pressure is gone.
The higher you go in the atmosphere, the less air pressure there is because the “thickness” of the air is less the higher you go. That’s why airplanes have “pressurized” cabins. We can’t survive in too little air pressure.
Today’s experiment will demonstrate just how strong air pressure is.
What You Need:
Take a straw and try to push it into an apple. Hard isn’t it? The straw bends. Now put your thumb over one end of the straw while you try to push the other end into the apple. Now what happens?
When you try to push the straw into the apple the air molecules in the straw are squished closer together. If your thumb is not over the opposite end of the straw the air molecules just spill out the end. However, if your thumb IS over the opposite end of the straw the air molecules are trapped. All those packed together molecules make the straw stay stiff so that it can push into the apple. The straw seems empty, but it isn’t, it is full of air molecules.
Here are some websites and books that will help you undertand air pressure:
When people and animals breath their bodies take oxygen into the lungs where it is passed into the blood. This is called respiration. There is another kind of respiration that goes on inside living organisms and that is called cellular respiration. During cellular respiration cells convert oxygen to carbon dioxide and water during a chemical reaction that happens inside the cell.
Yeast is a single cell organism that metabolized sugar and turns it into carbon dioxide and water. In this experiment you will be able to “see” the colorless, odorless gas that is carbon dioxide. You will know it is present because it will fill a balloon.
What You Need:
Empty Water Bottle
1 tsp Sugar
Put one packet of dry yeast into an empty liter soda bottle. Add about an inch of warm water to the yeast. Now add 1 tsp of sugar. Swirl this mixture around a little bit. Blow up a balloon and then let the air out again just to get it stretched a little. Now take the balloon and stretch its opening over the mouth of the water bottle. Check on the balloon every five minutes for the next half our or so. What happens to the balloon?
Science Experiment Idea: Try this experiment with three different soda bottles. Add the yeast to each one. Make your variable the substance you add to the yeast. Put water in bottle #1, soda in bottle #2, diet soda in bottle #3. You could try different kinds of juice, milk, etc. Which substance do you think will blow up the balloon the best? Why?
Here are some websites and books that will help you understand and explore yeast and cell respiration:
Google Preview – Science Experiments That Fizz and Bubble: Inflations Station (Pages 4-25)
Science Projects for Curious Kids – Yeast Feast (pages 91-92)
Words to Know:
Respiration – Breathing, bringing oxygen into the blood. Cell Respiration – The process cells use to convert oxygen into carbon dioxide and water. This is a little different than breathing. During cell respiration the cell takes in oxygen and gives off carbon dioxide during a chemical reaction inside the cell. This is the exact opposite of photosynthesis. During photosynthesis plant cells take in carbon dioxide and water and give off oxygen. Metabolic – A chemical reaction that happens inside a living organism. Yeast – A tiny little single cell fungus that can convert sugar into carbon dioxide. It makes a little chemical reaction all by itself. Carbon Dioxide -A colorless, odorless gas that is made by animals and people when they breath, or by cells when they respirate. Carbon dioxide is absorbed by plants during photosynthesis.
Animals on earth need a certain amount of heat to stay healthy and alive. How is it then, that animals like polar bars can survive in the arctic? How is it that whales can survive in the deep, freezing cold ocean? These animals have blubber, a layer of fat that acts as an insulator.
An insulator is a substance that prevents the transfer of heat or cold. The layer of blubber on a whale acts as a barrier to the cold of the ocean water. Because of its layer of blubber, the internal organs of the whale stay warm.
Your winter coat is an insulator. It keeps the cold in the winter air from making your body cold. It blocks the transfer of cold from the air to you. It also blocks the transfer of heat from your body to the air.
Here is an experiment that will show you how a simple insulator can make a big difference.
What You Need:
4 ziploc bags
Crisco Shortening or Vaseline
Fill a bowl with water and ice cubes. Put your hand inside one empty ziploc bag. Put that same hand with the bag on it inside a second ziploc bag. Now put your hand with the bags on it in the bowl of ice water. How long does it take for your hand to feel cold?
Ok, take your hand out of the bowl and take the bags off. Now fill one ziplic bag 1/2 full of Crisco or Vaseline. Put your hand inside one empty ziploc bag. Now put that same hand, with the bag on it, inside the bag full of Crisco or Vaseline. Squish the Crisco or Vaseline around so that it surrounds your hand. Now put your bag covered hand in the bowl of ice water. How long does it take for your hand to get cold?
The Crisco or Vaseline is an insulator, just like blubber. It stops the coldness of the ice water from transferring to your hand.
Words to Know: Insulator - A reduction of heat transfer between objects. Insulators keep cool things cool and warm things warm – like the thermos in your lunch box or the blubber on marine mammals. Heat - A high temperature. Blubber – A layer of fat that some animals have that helps keep the animals warm. Animals that have blubber include whales and sea lions, that live in the cold ocean and polar bears, that live in polar regions. Temperature – The level of heat present in a substance or of an object or person. Temperature is measured on a thermometer and expressed in number of degrees. Temperature can also be determined by using the sense of touch. Human skin is sensitive to changes in temperature.
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. What is left is the soft tissue that lined the inside of the eggshell. Today’s experiment is similar to the Bouncing Egg experiment. For this one, before you soak the egg in vinegar, you blow out the egg like you are going to decorate an Easter egg. This time, the egg will be empty when it soaks.
What You Need:
Straight Pin or Tack
Use a stright pin or a tack to poke a small hole in both ends of raw a egg. Hold the egg over the sink and blow on one end of the egg so that the yolk and egg white drain out the hole on the other side. Once the egg is empty soak the remaining egg shell in vinegar for a week. How does the egg look when you are done soaking it? Hold the egg in your hand and fold it in half. Now let go. What does the egg do? Toss the folded egg gently back and forth between your two hands. Now what does it do?
The vinegar dissolvs the hard shell of the egg. What you have left is the soft inner membrane of the egg. It LOOKS hard and still has an egg shape but it is soft, that’s why you can fold it. When you gently toss the egg back and forth btween your hands air enters through the two holes at either end of the egg. The egg blows back up, just like a balloon.
Here are some books websites that will help you understands acids and how they behave and the strange example of the folding eggshell:
Google Preview:Naked Eggs and Flying Potatoes (How to Make a Folding Egg page 89-91)
Words to Know:
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.
Black ink is black, right? Today you are going to find out. In this experiment you will be able to see all of the dye colors that mix together to make black ink.
What You Need:
Paper Towel or Coffee Filter
Several different kinds of black markers
Cut strips from the paper towel about 1 inch wide – one for each type of marker. Scribble across the bottom of one of the paper towel strips with each kind of marker. Scribble about one inch from one end of the paper towel strip. Tape the OTHER end of the strip to the maker you used to scribble on that strip. That will help you remember which marker goes with each paper towel strip.
Now hang the paper towel strips above the bowl of water so that only a little bit of the scribble end is in the water. Do not submerge the pen scribbles! Check on the paper towels in an hour. What has happened to the pen marks?
What you see happening on the paper towel strips is called chromatography. The color of the ink in markers is made by mixing different pigments together. A pigment is a substance that makes color, like ink or dye. To make black, several pigments are mixed together. When the end of the paper towel strip is submerged in water the water soaks up through the paper towel. When the water passes through the black ink marks it takes the pigment colors with it. Different colors of pigments travel with the water at different rates because the molecules of some pigments stick to the paper more strongly than others. So, as the water travels it separates the colors. This is called chromatography – separating the parts of a mixture so that you can see them one at a time. It looks like there is more than one way to make black!
Here are websites and books that will help you understand solutions and experiment with chromatography:
Mixtures and Solutions Chromatography (pages 34-38)
Words to Know:
Chromatography -A process that separates a mixture by passing it through something that will separate its parts. Mixture – A substance made by mixing two or more substances together. The molecules of the substances don’t join together so the substances can be easily separated. Homogeneous Mixture – A type of mixture that is the same throughout. Salt water and ink are good examples. Pigment- A substance used for coloring; ink, dye, etc.