SCIENCE BY KIDS FOR KIDS

2006 SUMMER SURPRISE WINNERS

I was at the ShangHai science muceum in China and this is me playing a game I call, mindball.You concentrate on the ball and the ball will move forword.If the opponent have more concentration,the ball would move torword you. If you move the ball to the opponents side, you win but if the ball gets to your side, you lose.(you can see I'm losing) I learned that the headband has a magnite and it will push the ball and it will only work if you concentrate.I like this vacation and I want to go back next year.

From,
Sunny

ICE CREAM
THE SCIENCE WAY

4oz of half & half or coffee mate
1 tbls sugar or 2 packets
1 tsp vanilla
1 good squirt ~ chocolate/strawberry etc
rock salt
1 sandwich baggie
1 gallon baggie
ice

1. Add all ingredients but rock salt to the sandwich baggie
2. Add rock salt & ice to gallon baggie
3. Put sealed sandwich baggie in gallon baggie with salt & ice
4. SHAKE, SHAKE & SHAKE (about 3 to 5 minutes)

HINTS:

Make sure the sandwich ziplock in completely closed - you don't want salt in your ice cream!!!

Wipe off the sandwich baggie before you open and eat your ice cream!~!

Thanks for this cool receipe ~

emailed by Nicole

Ice has to absorb energy in order to melt, changing the phase of water from a solid to a liquid. When you use ice to cool the ingredients for ice cream, the energy is absorbed from the ingredients and from the outside environment (like your hands, if you are holding the baggie of ice!). When you add salt to the ice, it lowers the freezing point of the ice, so even more energy has to be absorbed from the environment in order for the ice to melt. This makes the ice colder than it was before, which is how your ice cream freezes. Ideally, you would make your ice cream using 'ice cream salt', which is just salt sold as large crystals instead of the small crystals you see in table salt. The larger crystals take more time to dissolve in the water around the ice, which allows for even cooling of the ice cream.

You could use other types of salt instead of sodium chloride, but you couldn't substitute sugar for the salt because (a) sugar doesn't dissolve well in cold water and (b) sugar doesn't dissolve into multiple particles, like an ionic material such as salt. Compounds that break into two pieces upon dissolving, like NaCl breaks into Na⁺ and Cl^-, are better at lowering the freezing point than substances that don't separate into particles because the added particles disrupt the ability of the water to form crystalline ice. The more particles there are, the greater the disruption and the greater the impact on particle-dependent properties (colligative properties) like freezing point depresssion, boiling point elevation, and osmotic pressure. The salt causes the ice to absorb more energy from the environment (becoming colder), so although it lowers the point at which water will re-freeze into ice, you can't add salt to very cold ice and expect it to freeze your ice cream or de-ice a snowy sidewalk (water has to be present!). This is why NaCl isn't used to de-ice sidewalks in areas that are very cold.

LET NO FUTURE SCIENTIST BE LEFT BEHIND!!!

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AmyBeth@Spectrumofscience.com