Perhaps our brains are getting feverish from the heat, but some kitchen science experiments sounded like a cool way for kids and parents to survive the dog days of August.
We contacted a few experts, including Amy Senato, elementary science coordinator for the Mansfield school district, and Phil Parratore, science writer and retired eighth-grade science teacher.
"I would usually start my class with an 'explosion of the day,'" recalls Parratore.
Now that's what we call a cool teacher.
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Give us your coolest ideas for homegrown experiments, we begged these experts, ideas that will send shivers of excitement down our spines and teach us something about what "cold" really means. And make them fun, we added. Sure, we want the cold, hard facts, but we're looking to have a good time, too.
Our experts did their jobs well.
Fountain of youths
Materials: 16-ounce plastic soda bottle with a screw top; a large nail; a hammer; silicone sealant or caulk; a bucket; a straw.
Procedure: Have an adult use the nail and hammer to make a hole in the bottle cap that's big enough to fit the straw through. Place the straw through the hole so that it will extend about 6 inches into the bottle and fix it in place with the sealant or caulk. Let dry.
Fill the bucket with very hot water from the tap or have an adult heat water in a pot on the stove. Fill the bottle about three-quarters full with icy cold water. Quickly put the cap on the bottle, screw the cap on tightly and place one finger on the top of the straw to trap the air. Then place the bottle into the bucket of water, pause for a few seconds to allow the pressure to build and then release your finger from the straw.
Results: Water will shoot out the straw.
The cold, hard facts: The hot water from the bucket heats the water in the bottle, which heats the air in the bottle. Hot air takes up more room than cool air. The expanding air pushes on the water and it squirts out the straw.
Balloon deep freeze
Materials: One helium-filled balloon; a freezer.
Procedure: Place the balloon in the freezer. Look at it 30 minutes later. Take the balloon out and let it return to room temperature. Observe again.
Results: The balloon deflates in the freezer. It fills up again when it returns to room temp.
The cold, hard facts: Molecules that are cold move around less than molecules that are warm, and therefore cold gases take up less space than warm gases.
Materials: Large glass jar; two plastic sandwich bags; yardstick; string; tape; a tack; freezer.
Procedure: Place the glass jar in the freezer for about one hour. Tape one bag to each end of the yardstick with the open end on top so you can "pour" air into it. Tie one end of the string around the middle of the yardstick. Tack the other end of the string to the ceiling or the doorway and adjust the yardstick so that it is evenly balanced. Take the jar out of the freezer and immediately pour the cold air into one of the bags.
Results: The side with the cold air will tilt to the floor.
The cold, hard facts: Cold air is denser than warm or room-temperature air because it contains more air particles. As cold air flows from the container into the bag, it will cause an imbalance of the yardstick.
Materials: A small glass jar; clay; food coloring; a clear straw; a marker.
Procedure: Press a marble-size piece of clay into the inside bottom of the jar. Fill the jar with water and put a few drops of food coloring into the water. Wait till the food coloring spreads throughout the water. Slowly lower the straw into the water and press it into the clay so that the straw is standing up. Slowly pour out the water (leaving the water in the straw). Mark the height of the colored water on the straw. Place the jar in the freezer for several hours. Take the jar out of the freezer and observe the height of the ice.
Results: The water level has risen.
The cold, hard facts: Although, generally, liquids take up more room than solids, water is the important exception to that rule. That's because water freezes into a crystalline pattern.
(From Awesome, Magical, Bizarre & Incredible Experiments by Janice VanCleave, Wiley, 1994)
Materials: Large, good-quality balloon; a piece of dry ice
Safety note: It is essential to wear gloves when working with dry ice. Do not touch dry ice. Do this activity only under adult supervision. If the balloon is too small or the dry ice is too large, the balloon will burst.
Procedure: Place a quarter-sized piece of dry ice inside the balloon. Tie the neck of the balloon tightly.
Results: The balloon slowly expands.
The cold, hard facts: Dry ice is frozen carbon dioxide. When dry ice "melts," it sublimates, which means it goes directly from a solid to a gas, skipping the liquid phase.
Materials: Small piece of dry ice; 12-ounce clear plastic cup; piece of cardboard to fit on top of cup; scissors; water; food coloring (optional)
Safety note: Do not touch the dry ice. Do this activity only under adult supervision.
Procedure: Cut a round hole, about 1/2-inch wide, in the center of the cardboard. Fill the cup halfway with water. Add a drop or two of food coloring for effect. Place a marble-size piece of dry ice in the cup. Place the cardboard on the cup. Gently squeeze the cup while holding the cardboard in place.
Results: Misty smoke rings rise up.
The cold, hard facts: The smoke ring effect is due to the fairly high density of the cold, carbon-dioxide-filled mist.
Materials: 1 cup milk; 1/2 cup sugar; salt; 3 egg yolks; 1 teaspoon vanilla; 2 cups heavy whipping cream; 4 small zip-top sandwich bags; 4 large zip-top plastic storage bags; ice.
Procedure: Boil the milk with the sugar and a pinch of salt. Add the egg yolks while stirring and continue to stir. Let the mixture cool, and stir in vanilla and whipping cream. Divide the mixture into the four small sandwich bags. Seal bags securely. Place the small plastic bags inside the large zip-top plastic storage bags. Add ice cubes, a small amount of water and a good amount of salt to the large bags. Seal the large bags. Shake the bags and toss them around for about 15 minutes.
Results: Individual servings of ice cream
The cold, hard facts: It takes energy to separate the sodium and the chloride atoms of the salt molecules, which lowers the freezing point of the mixture. The ice cream solidifies faster than it would in your freezer because of this. Tossing the bags around mixes air into the ice cream.