Cabbage Juice Indicator - pH

by Liz LaRosa

www.middleschoolscience.com

 

click here for a printer friendly PDF version of this lab

Objectives:

Materials: (per group or station)

 

Procedure:

  1. Label your plastic cups #'s 1-6

  2. Choose one solution and pour a small amount into plastic cup #1.

  3. Write the name of the solution in your data table.

  4. Place a drop of  the solution onto red and then blue litmus paper.  Record results

  5. Add 1 - 2 tablespoons of red cabbage juice to the cup.  Record color change.

  6. Determine if the solution is a acid, base or neutral

  7. Repeat with solutions #2-6.

  8. 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

 

 

 

 

  

2

 

 

 

 

 

3

 

 

 

 

 

4

 

 

 

 

 

5

 

 

 

 

 

6

 

 

 

 

 

 

 

Results:

  1.  Name the acids, name the bases, were there any neutral solutions?

  2. What color did the cabbage juice turn to indicate a neutral substance?

  3. 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
Spectrum for Cabbage Water Indicator
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