Color Changers

Color Changers

Science Process Skills

observing

communicating

inferring

applying

measuring

Materials

red cabbage

plastic zip-top bag or bowl

hot tap water

container to hold strained cabbage liquid

tape

waxed paper

white paper

water

2 small cups

eyedropper

indicator

vinegar

baking soda

food samples: pickle juice, fruit juice, milk, buttermilk, cottage cheese, egg white, flour, etc.

Making the Indicator (to be done ahead of time)

Cut a 2 inch wedge of red cabbage.

Tear or cut the leaves into small pieces.

Put the cabbage pieces into a large zip-top plastic bag or a bowl.

Add enough hot tap water to cover the cabbage.

Soak the cabbage for at least 10 minutes.

Pour the liquid into a pitcher; discard the leaves or save for making a salad.

Doing the Activity

Take a strip of waxed paper to a table and put a piece of white paper underneath.

Pour water in one cup. Pour a small amount of indicator in a second cup.

Place 5 drops of indicator on the waxed paper; this puddle will serve as the control.

Place 5 more drops of indicator on the waxed paper making a second puddle. Rinse the eyedropper in water. Place 1 drop of vinegar on this puddle. Observe what happens. Add 1 or 2 more drops of vinegar and observe what happens. Rinse the eyedropper.

With an eyedropper place 5 more drops of indicator on the waxed paper, making a third puddle. Rinse the eyedropper in water. Place a very small pinch of baking soda in the puddle of indicator. Observe what happens. Add a second pinch and observe what happens.

Choose a food to test. Predict what will happen. Place 5 drops of indicator on the waxed paper, making a new puddle. Rinse the eyedropper. With the eyedropper or your finger place a sample of the food in a puddle of indicator. Observe what happens.

Repeat step 6 for each food to be tested. Remember to rinse the eyedropper between uses.

Reflecting

What color changes did you observe?

How can foods be grouped by the color changes?

What color change was observed most frequently?

What do the color changes have in common?

Applying

What happens if you don't rinse the eyedropper? What happens if drops from two puddles are combined? What made the color of the indicator change? What do foods with similar color changes have in common?

What's Happening

This experiment provides a simple way of exploring the acidic property of food by making an indicator from cabbage juice. The indicator allows you to observe a change in color when it is combined with an acid or base. The cabbage juice is a purple or bluish-purple color. Chemicals that turn it pink are called acids; chemicals that turn it green (or shades of blue and green) are called bases. Chemicals that don't cause a color change are called neutral. The color change that is observed is called a chemical reaction.

More Challenges

Test common nonfood household products such as aspirin, mouthwash, powdered cleaner

Make indicator paper- Cut up strips of white paper. Dip each strip into the cabbage juice and hold it there until the paper soaks up the juice. Lay the paper strips on a plate or waxed paper to dry. Dip one end of a dried strip in a liquid you want to test. To test solids such as baking soda, dissolve a sample in water.

Make dirty pennies shine! Drop a dirty penny in one of the liquids tested. Take the coin out the next day. What happened?

Activity Source

"Kitchen Science for Kids," Cornell University Resource Center, 7 Business and Technology Park, Ithaca, NY 14850, (607) 255-2080, FAX (607) 255-9946, order # 399KS.

IOWA STATE UNIVERSITY
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	Color Changers
	Science Process Skills observing communicating inferring applying measuring
	Materials red cabbage plastic zip-top bag or bowl hot tap water container to hold strained cabbage liquid tape waxed paper white paper water 2 small cups eyedropper indicator vinegar baking soda food samples: pickle juice, fruit juice, milk, buttermilk, cottage cheese, egg white, flour, etc.
	Making the Indicator (to be done ahead of time) Cut a 2 inch wedge of red cabbage. Tear or cut the leaves into small pieces. Put the cabbage pieces into a large zip-top plastic bag or a bowl. Add enough hot tap water to cover the cabbage. Soak the cabbage for at least 10 minutes. Pour the liquid into a pitcher; discard the leaves or save for making a salad.
	Doing the Activity Take a strip of waxed paper to a table and put a piece of white paper underneath. Pour water in one cup. Pour a small amount of indicator in a second cup. Place 5 drops of indicator on the waxed paper; this puddle will serve as the control. Place 5 more drops of indicator on the waxed paper making a second puddle. Rinse the eyedropper in water. Place 1 drop of vinegar on this puddle. Observe what happens. Add 1 or 2 more drops of vinegar and observe what happens. Rinse the eyedropper. With an eyedropper place 5 more drops of indicator on the waxed paper, making a third puddle. Rinse the eyedropper in water. Place a very small pinch of baking soda in the puddle of indicator. Observe what happens. Add a second pinch and observe what happens. Choose a food to test. Predict what will happen. Place 5 drops of indicator on the waxed paper, making a new puddle. Rinse the eyedropper. With the eyedropper or your finger place a sample of the food in a puddle of indicator. Observe what happens. Repeat step 6 for each food to be tested. Remember to rinse the eyedropper between uses.
	Reflecting What color changes did you observe? How can foods be grouped by the color changes? What color change was observed most frequently? What do the color changes have in common?
	Applying What happens if you don't rinse the eyedropper? What happens if drops from two puddles are combined? What made the color of the indicator change? What do foods with similar color changes have in common?
	What's Happening This experiment provides a simple way of exploring the acidic property of food by making an indicator from cabbage juice. The indicator allows you to observe a change in color when it is combined with an acid or base. The cabbage juice is a purple or bluish-purple color. Chemicals that turn it pink are called acids; chemicals that turn it green (or shades of blue and green) are called bases. Chemicals that don't cause a color change are called neutral. The color change that is observed is called a chemical reaction.
	More Challenges Test common nonfood household products such as aspirin, mouthwash, powdered cleaner Make indicator paper- Cut up strips of white paper. Dip each strip into the cabbage juice and hold it there until the paper soaks up the juice. Lay the paper strips on a plate or waxed paper to dry. Dip one end of a dried strip in a liquid you want to test. To test solids such as baking soda, dissolve a sample in water. Make dirty pennies shine! Drop a dirty penny in one of the liquids tested. Take the coin out the next day. What happened?
	Activity Source "Kitchen Science for Kids," Cornell University Resource Center, 7 Business and Technology Park, Ithaca, NY 14850, (607) 255-2080, FAX (607) 255-9946, order # 399KS.