Category Archives: Science Experiments

Acids – Bouncing Egg

Acids – Bouncing Egg

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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 vinegar 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:

Here are some books that will help you investigate bouncing eggs.

  • Google Preview: How to Make a Bouncing Egg
  • Google Preview: Science Experiments That Surprise and Delight (Bouncing Egg page 22-23)
  • Google Preview: Naked Eggs and Flying Potatoes (Naked Egg page 83-87)
  • Kitchen Science Experiments: Naked Eggs (pages 45-47)
Acids and Bases That Surprise and Delight Naked Eggs and Flying Potatoes Kitchen Science Experiments
How to Make a Bouncing Egg

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.

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Surface Tension – Sand Castles

Surface Tension – Sand Castles

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If you have ever tried to build a sand castle you know that there is a certain kind of wet sand that is perfect for it. If there is too much water in your bucket the mixture is too soupy. If you don’t have enough water in your bucket the sand won’t hold a shape and just crumbles. Why does the perfect mixture of sand and water work? Surface tension. Surface tension is the attraction that happens between water molecules. Water molecules are attracted to each other. The surface of water has an elastic quality because the molecules are hugging close together. This is why some insects can walk on water.

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. This is called cohesion. The molecules hug so close together they don’t want to touch other molecules around them. That’s why a bubble or a drop of water is round and only rests a small part of itself on a surface when it lands.

When you add sand to water, the surface tension of the water forms little elastic bridges between the grains of sand. When the ratio of sand to water is just right these bridges are the perfect strength for building sand castles. In today’s experiment you will be able to watch these bridge at work and figure out the best recipe for building sand castles.

What You Need:

  • 12 Dixie Cups
  • Sand
  • Water
  • 25 Pennies
  • 4 Large Plates
  • Large Bowl
  • Measuring Cups (1/4, 1/3, 1/2, 1)

You are going to test what ratio of sand to water is the best one for building a strong sand castle. Label each plate – label the first one 1/4 cup, the second one 1/3 cup, the third one 1/2 cup and the last one 1 cup.  For each trial you are going to use 1 cup of sand. The variable in this experiment is going to be the amount of water you add to the sand. For the first trial mix 1 cup sand and 1/4 cup water in the bowl. Fill three dixie cups with this mixture and turn them over to make small sand castles in the plate labelled 1/4 cup. Do the castles flatten or stay formed like the dixie cup? If any of them stay formed, stack pennies on top of the little castle one at a time until the little castle collapses. Write down how many pennies each little castle could hold.  Repeat this test using 1 cup sand and 1/3 cup water, 1 cup sand and 1/2 cup water and 1 cup sand and 1 cup water. Keep track of your results on a chart like this:

Amount of Water #pennies trial #1 #pennies trial #2 #pennies trial #3
1/4 Cup
1/3 Cup
1/2 Cup
1 Cup

One cup of sand to 1/3 cup water is what worked for us!

It turns out that water molecules attract to each other and they ALSO attract to sand. If you have a good balance of sand to water…nice and sticky…then you get a strong sand castle. If there is too much sand the mixture is too dry and the castle crumbles. If there is too much water the mixture is too wet and oozes all over the place.

More IndyPL Experiments about Surface Tension:

Words to Know:

Mixture – A substance made by mixing two or more substances together.

Surface Tension – The film that forms on the surface of liquids caused by the attraction of the particles in the surface.

Cohesion – The attraction between like molecules; to stick together.

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Surface Tension – Soap Bubbles

Surface Tension – Soap Bubbles

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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.

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. This is called cohesion. The molecules hug so close together they don’t want to touch other molecules around them. That’s why a bubble is round and only rests a small part of itself on a surface when it lands.

When you blow air into soap bubble solution the liquid molecules want to attract to each other again so they wrap around the burst of air until they can attach to each other again – this is what makes the round bubble shape. The air inside the solution is pushing the molecules in the soap bubble solution apart but the attraction between the soap bubble solution molecules is so great, the bubble doesn’t pop – the molecules are hugging each other too tight.

To experiment with bubbles you need a good bubble recipe. Below are some simple recipes to try. Each of the recipes use water and dish soap. The “other” ingredient can be baking powder, corn syrup, glycerin (sold at the pharmacy) or sugar. We had the best luck with baking powder. The baking powder recipe made some HUGE bubbles.

Science Project Idea:

Mix different formulas of bubble mix and test them to see which one makes the best bubbles. Use the same amount of water and the same amount of dish soap in at least three different buckets. Choose one “Other” ingredient and add it in different amounts to each of your trial buckets. To be fair, you should hold the bubble wand in front of a fan instead of trying to blow on it, that way you know that the amount of air being blown to make the bubble will be exactly the same. Test the three formulas several times and record your results on a chart. Decide before you begin what property you are looking for in the bubbles. Are you going to test which formula makes the biggest bubble, the bubble the last the longest without popping or the formula that makes the most bubbles?

Here are some books and websites that will help you understand and have fun with bubbles:

  • Exploratoriuam: Bubbles
  • Bubblesphere
  • Homemade Bubble Solutions
  • The Ultimate Bubble Book There are 3 fun activities in this book – Person Inside a Bubble (Page 41) Giant Bubbles (Page 48-51) Printing With Bubbles (Page 52-53)
  • Google Preview: Science Experiments That Explode and Implode: Stink Bombs (bubbles that stink! pages 22-23)
  • Prize Winning Science Projects for Curious Kids: The Bubble Olympids (pages 102-103)

More IndyPL Experiments about Surface Tension:

Ultimate Bubble Book How to Make Bubbles Science Experiments That Explode and Implode Prize Winning Science Projects

Words to Know:

Surface Tension – The film that forms on the surface of liquids caused by the attraction of the particles in the surface.
Cohesion – The attraction between like molecules; to stick together.

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Surface Tension – Pepper Scatter

Surface Tension – Pepper Scatter

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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:

  • bowl
  • water
  • pepper
  • toothpicks
  • dish soap

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:

More IndyPL Experiments about Surface Tension:

Science Experiments that Fly and and Move: Surface Magic (pages 6-7)

Science Experiments that Fly and Move Water Science Fair Projects

Words to Know:

Surface Tension The film that forms on the surface of liquids caused by the attraction of the particles in the surface.
Cohesion – The attraction between like molecules; to stick together.

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Static Electricity: Salt & Pepper Separater

Static Electricity: Salt & Pepper Separater

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To understand electricity, you have to first understand the atom, the basic building block of all matter. Matter is all of the “stuff” in the universe. Matter is made up of atoms. Atoms have a nucleus, an inner core that is made up of neutrons which have no charge, and protons which have a positive charge. Atoms also have orbitals, particles that are located around the nucleus. These are called electrons and these have a negative charge.

If you had some salt and pepper and you mixed the two together, how long would it take you? Not long if you know how to do it.

What You Need:srpstaticpepperpour

  • Salt
  • Pepper
  • Plate
  • Balloon
  • Measuring Spoon

Blow up the balloon and tie it closed. Pour 1 teaspoon salt and 1 teaspoon pepper onto the plate and stir it around. Rub the balloon back and forth quickly on the top of your head. Now hold the balloon close to the plate. What happens to the pepper flakes? What happens to the salt flakes?

Here are some websites that will help you understand how static electricity works:

srpstaticpepperstickWhen you rub the balloon on your hair the friction caused by the hair and the balloon rubbing against each other causes the electrons from your hair to transfer to the balloon. This gives the balloon a negative charge. When you held the balloon over the dish of pepper, the pepper stuck to the balloon because the pepper has protons and a positive charge. Just like with magnets…opposites attract.

Science Experiments That Surprise and Delight Salt and Pepper Separator (page 10-11)

That Surprise and Delight All Charge Up a Look at Electricity Understanding Electricity Electricity
Electricity Explore Electricity

Words to Know:
Electricity – Energy that comes from charged particles like electrons or or protons.
Static Electricity – An electric charge that is caused by friction. It typically causes a spark or a crackling sound. It can also make light things move…like hair or dust or a feather.
Electron – The part of the atom that has a negative charge. Electrons are orbital, meaning they are not located in the atom’s nucleus.
Proton (positive) – The part of the atom that has a positive charge. It is located in the atom’s nucleus.
Neutron – The part of an atom that has no electric charge. It is located in the atom’s nucleus.  (Except hydrogen…that one kind of atom does not have any neutrons.)
Nucleus – The positively charged The central core of an atom. It is positively charged because that is where the proton’s are.

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