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Friday, October 30, 2009

Chemistry

Program Covered:
Beyond You – Try new things #4
Chemistry Badge #1, #2, #5, #8
Engineering Badge #4
Science Badge #3, #4
Tasty Treats Badge #3


Materials Required: See each activity individually

Opening

Station One: Science in the Deep Freeze!

Materials:
Whole Milk, Cream, or Half & Half
Vanilla extract or chocolate syrup
sugar
ice
salt
several large Ziploc-style bags
1 small Ziploc-style baggie for each person

Each person should have her own sandwich size Ziploc-style baggie to mix the ingredients in.
Add 5 grams (1 teaspoon) of sugar.
Add 60 ml (4 tablespoons) of milk, cream, or Half & Half.
Add a dash of vanilla extract or about 2.5 ml (1/2 teaspoon) of chocolate syrup.
Seal the small baggies and squish everything around to mix it up.
Take the large Ziploc-style bag and fill it half full of ice.
Next, add approximately 150 grams (10 tablespoons) of salt to the large bag.
Take a few of the small baggies and place them into the large bag with the ice and salt (maximum of 3-4 small baggies at a time). Seal the large bag.
Carefully shake the large bag for about 5 minutes.
What is happening to the contents in the small baggies?
Pass out spoons and eat!

What is happening?
Water freezes at a temperature of 0 degrees Celsius (32 degrees Fahrenheit). As the water is cooled, the water molecules slow-down, and when the temperature reaches 0 degrees

Celsius (32 degrees Fahrenheit) the water molecules bundle together, not quite immobile, and make ice. The freezing point of salty solutions is lower than 0 degrees Celsius. So when you add salt to the ice, it can turn liquid and still be at 0 degrees or lower. Since liquids are able to “share” their coldness better than solids, you will be able to make ice cream faster if you add salt to the ice, causing your bag to be filled with extra-cold water!

Station Two: Slippery Stuff
You’ll need:
oil
soap
water

Rub a few drops of cooking oil on your hand.
Wash your hands with water? What happens?
Wash your hands with soap. Does this make the slippery oil go away?
Why do you think you should wash your hands with soap before you eat?

What is happening?
The water molecules stick together tightly and will not mix with the oil on your hand. Soap molecules are friendly with both water and oil. One end of the soap molecule sticks to oil, the other end sticks to water. The soap breaks up the surface tension and keeps the oil drops mixed in with the water so that the oil can be washed off your hand.

Station Three: Ack, It’s Gak!

You’ll need:
1/4 cup cornstarch
3-1/2 teaspoons water (add more if needed)
a bowl
food colouring (optional) (Watch out for stains!)

Add cornstarch to water in a bowl. Mix with hands (not spoon; needs warmth of hands).
When you touch the mixture gently, it should yield like a liquid. When you smack your hand down on it, it should resist like a solid. Add colouring if wanted. Play away!

What is Happening?
Substances can be solid, liquid or a gas (states of matter). This change between states can occur when there is a change of temperature or pressure. Gak is borderline between a solid and liquid.

Station Four: Mix ‘n Match

You’ll need:
pH kit
vinegar, water, and ammonia
1 cup for clean water
1 cup for the waste liquid
plastic syringe
paper towel

Put your gloves and glasses on and spread the paper towel on the tabletop.
Take the red lid off the pH tester. The yellow side is for chlorine so we won’t need it.
Use the syringe to take some of the liquid out of one of the containers labeled ammonia, water, or vinegar and place it in the pH tester.
Fill up to the MAX line.
Add 5 drops of the phenol red dye, put the lid on tightly and shake it a bit.
The liquid will have changed colour. Look to the left and match the colour and the number.
Now look on the pH scale above to find out if the liquid is an acid or a base (alkaline).
Pour the used liquid into the waste cup
Use some clean water to rinse out the kit with the syringe.
Now repeat with the other two liquids

What is happening?
An indicator is a special type of compound that changes colour depending on the pH of the solution you mix it with. The phenol red dye that you have in your pH kit is an indicator.

Test all kinds of different liquids. Start with the liquids you drink, such as pop, milk, and juice. Then take the pH kit on a hike and sample a creek, river, pond or puddles of water.

Station Five: Bouncy Ball

You’ll need:
3 clear cups (5 ounce plastic cups work well)
Water
Borax (from the detergent aisle at the supermarket)
White liquid glue
Food coloring
2 spoons

Fill one cup halfway with water and add a spoonful of borax. Stir. Some of the borax should still be visible at the bottom after you stir.
Add enough white glue to the second cup to fill it a quarter of the way. Add an equal quantity of water so the cup is half full (this is to the cup of glue). Then add a drop or two of food coloring. Stir this together with the second spoon.
Pour half of the coloured glue and water mixture into the third cup. Add an equal amount of the borax and water mixture to the third cup.
Stir this combination together. It will change to something very different.
Take out the putty, squeeze out the liquid, and roll it into a ball in your hands. Test to see if your ball will bounce when you drop it on a hard surface.


Closing

Leave nametags for next week

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