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Sample Experiments from Grippy and Cormo's

71 Splashy Experiments

Materials needed for this experiment:

glass filled with water

ice cube

salt

string

Put the fresh ice cube right out of the freezer into the glass of water. Think you can lift the ice cube out of the water with this piece of string, using only one hand? Here's how:

Get the string wet by pushing it under the water. Let the string soak up water while you do the next step.

Sprinkle salt on top of the floating ice cube. Let it sit there for one minute.

Now remove the string from the water. Lay one end of the wet string across the salted ice cube. Let the wet string sit on the salted ice for one minute. Now, pick up the loose end of the string __ the ice cube will lift out of the glass.

 

What happened? Salt melts ice and dissolves in the water (we'll do experiments with dissolving later). After the salt dissolved, the water was no longer just water __ it was salt water. The salt water froze back into place, and glued the wet string with it. Remember sticking the two ice cubes together, earlier? (This is thin glue, so don't shake the ice around or the glue will crack, and the ice cube will fall off the string.)

Materials needed for this experiment:

cup with sealing lid

water

First Experiment: Fill the cup with water, all the way to the brim. Carefully put the filled cup on a flat surface in your freezer or the freezer section of your refrigerator near the ice cubes or the ice cream. Let the glass sit in the freezer over night. In the morning, look at the water level. It looks like the water grew as it froze. If you live in a neighborhood where milk is delivered and the weather freezes, you may have seen milk freeze in its bottle and pop its top.

Second Experiment: This time we'll try to keep the water from growing as it freezes. Use the plastic cup with the fitted lid. Fill the cup. Put the lid on, and seal it in place. Put the cup in the freezer or ice box over night again. In the morning see what happened.

You can try this experiment with even tougher materials than plastic. You might use an old metal paint can, or an old plastic medicine bottle with a screw_top lid. You could even put a heavy rock or brick on top of the container. See if you can keep water from growing as it freezes. Don't do this experiment in glass containers.

Water is one of the few liquids that takes up less room when it is liquid than when it is solid. (If you've ever made candles, you've seen that wax shrinks as it cools. Most liquids shrink like wax, instead of growing like water.) One way you can tell that water grows when it freezes is to see that ice floats on water. Ice cubes float in a glass of water. Ice always forms at the top of the lake. Ice and water are chemically the same, but ice is solid and water is liquid. Ice floats on water, even though they are the same material, because the molecules of water take up more space when they form crystals in the ice, and they are packed together more tightly in the water. When the same material takes up more room, it becomes less dense. The less dense material always floats on top. We'll work with density later in this activity book.

Materials needed for this experiment:

straw

drinking glass

If you've ever seen scientists on the news or in movies, you've seen pipettes. Pipettes are the glass or plastic tubes that scientists use to measure and carry liquids. You can do the same thing with a drinking straw.

This trick is most fun if you can do it in a transparent glass, where you can see the water level. Fill the glass to within an inch of the top. Put the straw in the water, leaving the top end out of the water. Look carefully at how deeply the straw is in the water. If you want, draw a line with a marker at the place where the straw starts to come out of the water. Now, put tightly one finger over the top of the straw (see diagram) and put your thumb and other fingers on the sides of the straw. Lift the straw out of the water. See how high the water comes in the straw. Is it the same height as the line you drew? Now, lift the finger that is covering the top of the straw. What happens? Why did the water stay in the straw when it was open at the bottom all the time? Remember what happened with the glass of water and the card in experiment #12 When air couldn't get in, the water couldn't get out. Water blocked the hole at the bottom of the straw. (Remember, water sticks to itself.) When you lifted your finger off the top of the straw, air finally had a way to get in. Try putting the straw different depths into the water, putting a finger over it, and lifting it up. Can you collect water in the straw at a different height from the water level? Next time you see scientists using pipettes look for a bulb on top of the pipette. See if you can figure out what the bulb is doing. You can do the same thing with your mouth __ but NEVER use your mouth to suck on a real pipette. You don't want chemicals from a scientific laboratory anywhere near your mouth!

What else can you do with a pipette besides carry water around? Use food coloring to make a glass of red water and a glass of blue water. Place a pipette into each glass. Using a third glass, mix a pipette full of red water with a pipette full of blue water. What happens? Try using different amounts of red and blue. Try using yellow food coloring. You can also do this with the red cabbage experiment later in this book.