...because the simplest of words become stories for a lifetime...
Bouncing egg
or decomposition reaction III
Can you peel an uncooked egg?
Materials needed:
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glass or jar
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egg
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vinegar
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Instructions:
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Gently put your egg in a glass or jar (if you want to avoid the smell).
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Top up with vinegar until the egg is covered.
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Wait for 24 hours. Then take the egg out and gently rinse it.
The science behind:
Decomposition reaction: Eggshells contain calcium carbonate, which reacts with acetic acid found in vinegar. The acetic acid breaks up the shell into calcium and carbonate, thus dissolving the shell. While the calcium floats away, the carbonate reacts with the acetic acid to create carbon dioxide that can be seen around the egg.
Suggestions:
-
Experiment with different liquids, for example, water or milk.
Oil fireworks
or hydrophobic effect
What happens if you try to colour oil?
Materials needed:
-
2 glasses and a spoon
-
oil and food colouring
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water
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Instructions:
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Fill your glass with water.
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In a second glass, pour oil and add several drops of food colouring. You might add several colours if you like.
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Pour the oil in the glass of water and observe.
The science behind:
Water molecules (hydrophylic) are polar and one end has a slight negative charge, the other a slight positive charge. Those charges let the molecules form hydrogen bonds and attach to other molecules that are polar, including other water molecules. Oil molecules (hydrophobic), however, are non-polar, and they can't form hydrogen bonds.
Suggestions:
-
Experiment with different liquids, for example, oil and milk.
Frozen oil fireworks
or hydrophobic effect
What happens if you try to freeze oil?
Materials needed:​
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oil and food colouring
-
water
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glass
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Instructions:
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Mix oil with colouring and freeze immediately.
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After the oil is frozen put it in a glass of water and see it melt.
The science behind:
Vegetable oil consists of molecules in long chains called lipids, usually with a mixture of molecules of different sizes and shapes. That makes it hard for the oil to form a regular crystal, suppressing ordinary freezing. Furthermore, oil is hydrophobic (see above) and doesn't mix with water.
Suggestions:
-
Experiment with different oils and animal fat, which one freezes best?
Sugar rainbow
or water density
Have fun stacking up rainbow water and wonder why doesn't it mix?
Materials needed:
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cups
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spoon
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warm water
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sugar
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pipette
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vial or a tall glass
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food colouring
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Instructions:
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Put out your cups, one for each colour you intend to use.
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Put no sugar in the first cup. Then 1 teaspoon in the second cup, 2 teaspoons in the third cup and so on.
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Add 100ml of warm to hot water and mix until the sugar is completely dissolved.
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Add your colouring and mix.
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Take your pipette and pour water from your cup with most sugar at the bottom of the cup. Then work your way up to the cup with no sugar, pouring the water very gently.
The science behind:
Water density: Density is defined as mass divided by volume. As you add sugar to the water, more and more sugar molecules will take over space, making the water denser. A sucrose molecule is larger and it will displace the lighter water molecule: it's a bigger molecule so each sucrose can displace more than one water, therefore it will be at the bottom pushing the lighter molecule above it, creating layers.
Suggestions:
-
How many colours can you layer up?
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Try using oil as the last layer.
Lava lamp
or water density and hydrophobic effect
Water and oil experiments are a must and they would not be complete without a lava lamp.
Materials needed:
-
glass
-
oil
-
water
-
effervescent tablets (any sort will do, preferably without colouring)
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food colouring
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Instructions:
-
Add water to your glass (about 2/3- 3/4 full). Add colouring.
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Pour oil to fill the cup.
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Drop in the tablet and enjoy. You can keep adding the tablets as many times as
you like.
The science behind:
Density: The molecules that make up the oil are larger than those that make up water , so they cannot pack as tightly together as the water molecules can (that are made up of two hydrogen atoms and one oxygen atom each) and are less dense, therefore they float on top.
Hydrophobic effect: Water molecules (hydrophylic) are polar and one end has a slight negative charge. Oil molecules are (hydrophobic)non-polar, and they can't form hydrogen bonds- therefore they don't mix.
Suggestions:
-
Try using different ratios of oil to water
Ice pyramid
or freezing point depression
This is a combined experiment. First, try to build the pyramid as the ice is melting and then decorate it with salt and colouring!
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Materials needed:
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Ice
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salt
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food colouring
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Instructions:
-
Prepare your ice cubes and build a pyramid.
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Sprinkle your salt. Add a few drops of food colouring.
The science behind:
Freezing point depression: The salt’s structure makes it more difficult for the water molecules to form the rigid formation they need to be in to become ice. Salt lowers the freezing point of water and it means that the water will not freeze until it has reached a lower temperature than the normal freezing temperature of 0 degrees Celsius.
Suggestions:
-
What happens if you use sugar?
-
You have to hurry up or the ice melts in your hands!
Ice fishing
or freezing point depression II
Do you like fishing but cannot go out? It is easy, just fish some ice!
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Materials needed:
-
ice
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salt
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food colouring (optional)
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glass with water
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straw or any stick
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yarn or a string
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modelling clay or small fish toys
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Instructions:
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Model your fish out of clay and let dry. If you have small fish use those and put them in your ice cube tray.
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Prepare your fishing rod by tying a string on it.
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Pour water in your glass and put your cubes in (make sure the water is cold or the cubes melt quickly.)
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Prepare to fish by putting the string of your fishing rod over ice and sprinkle your salt on where the cube touches the string.
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Wait for a few seconds (about 30) and take your fishing rod out.
The science behind:
Freezing point depression: Salt lowers the freezing point of water and it means that the water will not freeze until it has reached a lower temperature than the normal freezing temperature of 0 degrees Celsius, but when the ice is surrounded water and freezing temperatures, it quickly freezes again, causing ice to form again over the string.
Suggestions:
-
Have a competition how many fish have you caught?
Traffic light
or oxidation
This is a fun experiment for hours of shaking!
​
Materials needed:
-
40 mL 10% glucose solution;
-
25 mL 10% indigo carmine solution;
-
150 mL 1 M sodium hydroxide solution
-
water
-
bottle
-
stirrer
-
2 beakers
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Instructions:
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In a glass or beaker combine water and glucose.
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Add indigo carmine and stir.
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Add hydroxide solution, wear goggles and protective glass. Transfer to a bottle and shake freely.
The science behind:
Oxidation: In an alkaline medium, blue indigo carmine turns green as it is oxidized by the oxygen in the air. Glucose then gradually reduces the indigo carmine, changing its color first to red, then to yellow. If the flask is shaken, the oxygen contained in the air oxidizes the indigo carmine, turning it back to green. The solution will continue to change colors until all of the glucose has been oxidized!
Suggestions:
-
Try to experiment with different ratios, what differences do you see?