Juice for Sleuths

Sleuths find out information and use it to solve mysteries.  In this experiment, you will discover how to use the juice from purple cabbage to determine the properties of a solution.  Solutions are mixtures.  You will make solutions of stuff mixed with water.  

Acidic solutions all have a low pH, your stomach is full of an acidic solution.  Coffee, vinegar, tea and Pepsi are all acidic solutions.  

Basic solutions all have high pH, baking soda can be mixed with water to make a basic solution.

You will first make a solution from mixing purple cabbage and water, and you will use this solution to test for acids and bases.  Then, you will observe what happens when acidic and basic solutions are mixed.

Materials:
Reaction tray Cut up purple cabbage
wooden stick Vinegar
Plastic pipets Baking soda
Water bottle Lemon juice
Plastic freezer bag Milk of Magnesia

Part I.  Making the Cabbage Solution
1.  Put a handful of purple cabbage into a freezer bag.
2.  Cover the cabbage with water from the water bottle
3.  Seal the bag!
4.  Gently squeeze the bag, to mix the cabbage with the water.
5.  When the solution is deep purple, stop squeezing and go on to the next part.

Part II.  Testing for Acids and Bases
1.  Use your reaction tray and the pipet to put vinegar into one well of the reaction tray.
2.  Use a wooden stick to put a small amount of baking soda into a well of the reaction tray.  Then add water to this well.
3.  Use a pipet to add cabbage juice to each well.  

    Record your results:
Solution  Color Acidic or Basic?
Vinegar
Baking Soda

Part III.  New Solutions!
1.  Use a pipet to put lemon juice into the reaction tray.
2.  Use a pipet to put milk of magnesia into the reaction tray.
3.  Use a pipet to add cabbage juice to each well.

Record your results:
Solution Color Acidic or Basic?
Lemon juice
Milk of Magnesia

Part IV.  Mixing them up!
1.  Use a pipet to mix vinegar with baking soda
2.  Use a pipet to mix lemon juice with milk of magnesia
3.  Clean out your reaction tray and try other mixtures!

Record your results:
Mixture New color?  What else happened?
Vinegar + Baking soda
Lemon Juice + Milk of Magnesia

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Summarize your results.  Write complete sentences to answer the following questions.

1.  Describe the color of the solution when cabbage juice was mixed with vinegar.
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2.  Describe the color of the solution when cabbage juice was mixed with baking soda.
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3.   What kind of solution is lemon juice?  How do you know this?
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4.  What kind of solution is Milk of Magnesia?  How do you know this?
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5.  Describe what happened when vinegar was mixed with  baking soda.
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6.  Describe what happened when lemon juice was mixed with Milk of Magnesia.
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7.  Describe your other combinations.
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8.  What did you learn from this experiment?
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