Cabbage Juice Indicator - pH
by Liz LaRosa
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Objectives:
to test household solutions with litmus paper
to test household solutions using red-cabbage juice indicator
to classify household substances as acids or bases
to determine the pH range of red cabbage juice
Materials: (per group or station)
Beaker of Red Cabbage Juice - recipe
Red and Blue Litmus Paper
6 Plastic cups
Beakers of the following solutions: water, baking soda, vinegar, salt, sugar, lemon juice, soda, etc...
Plastic spoon
black marker
Procedure:
Label your plastic cups #'s 1-6
Choose one solution and pour a small amount into plastic cup #1.
Write the name of the solution in your data table.
Place a drop of the solution onto red and then blue litmus paper. Record results
Add 1 - 2 tablespoons of red cabbage juice to the cup. Record color change.
Determine if the solution is a acid, base or neutral
Repeat with solutions #2-6.
Clean up. Pour contents into sink and throw out used cups.
Data Table:
|
Plastic Cup # |
Solution |
Red Litmus |
Blue Litmus |
Red Cabbage Juice |
Acid/Base or Neutral |
|
1 |
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2 |
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3 |
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4 |
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5 |
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6 |
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Results:
Name the acids, name the bases, were there any neutral solutions?
What color did the cabbage juice turn to indicate a neutral substance?
Why is it important to use both blue and red litmus paper to determine pH?
Conclusion:
2-3 sentences on what you learned
How to read pH paper:
Red Litmus Paper – Stays Red = Acid or Neutral
Turns Blue = Base
Blue Litmus Paper – Stays Blue = Base or Neutral
Turns Red = Acid
Colors of Cabbage Juice:
acid neutral base
0 1 2 3 4 5
6 7 8 9 10 11 12
13 14
http://www.middleschoolscience.com
Modified from these lessons:
http://www.science-house.org/learn/CountertopChem/exp27.html
http://www.miamisci.org/ph/lpexplore1.html