1. Primary School in Chalin
eTwinning Club
RED CABBAGE PH INDICATOR
Ania & Bartek
Class 6
2. THE PURPOSE OF THIS EXPERIMENT IS TO SHOW
HOW TO MAKE YOUR OWN PH INDICATOR USING
CABBAGE JUICE
3. RED CABBAGE JUICE CAN BE USED TO
TEST THE PH OF COMMON HOUSEHOLD
CHEMICALS.
RED CABBAGE JUICE CONTAINS
A NATURAL PH INDICATOR THAT CHANGES
COLORS ACCORDING TO THE ACIDITY OF
THE SOLUTION.
4. To make our own red cabbage juice indicator we need:
* red cabbage
* blender or knife
* boiling water
Procedure
Chop the cabbage into small pieces until you have about 2 cups of
chopped cabbage. Place the cabbage in a large beaker or other glass
container and add boiling water to cover the cabbage. Allow at least
ten minutes for the color to leach out of the cabbage.
Filter out the plant material to obtain a red-purple-bluish colored liquid.
This liquid is at about pH 7.
Ania and Bartek prepared pH indicator a day before their experiment.
6. Set out 5 glasses, side by side.
Fill each glass half full with cabbage juice.
7. Add a lemon to the glass of
cabbage juice
We noticed the color
changed to red, which
indicated that lemon
juice is classified as an
acid.
8. Add a little vinegar to the glass
of cabbage juice
We noticed the color
changed to red, which
indicated that vinegar is
classified as an acid.
9. Add a teaspoon of laundry detergent
to the glass of cabbage juice
We noticed the liquid
turns green, indicating
that this chemical is a
base.
10. Add a teaspoon of oven cleaner
to the glass of cabbage juice
We noticed the color
changed to green,
which indicated that the
oven cleaner is
classified as an base.
11. Add a teaspoon of alka-prim tablets
to the glass of cabbage juice
We noticed the color
changed to green,
which indicated that
alka-prim tablets are
classified as an base.
12. DURING OUR EXPERIMENT THE PURPLE
CABBAGE JUICE TURNED RED WHEN IT
WAS MIXED WITH SOMETHING ACIDIC
AND TURNED GREEN WHEN IT WAS
MIXED WITH SOMETHING BASIC. RED
CABBAGE JUICE IS CONSIDERED TO BE
AN INDICATOR BECAUSE IT SHOWED US
SOMETHING ABOUT THE CHEMICAL
COMPOSITION OF OTHER SUBSTANCES.
13. RED CABBAGE CONTAINS A WATER-SOLUBLE
PIGMENT CALLED ANTHOCYANIN THAT
CHANGES COLOR WHEN IT IS MIXED WITH AN
ACID OR A BASE.
THE PIGMENT TURNS RED IN ACIDIC
ENVIRONMENTS WITH A PH LESS THAN 7 AND
THE PIGMENT TURNS BLUISH-GREEN IN
ALKALINE (BASIC) ENVIRONMENTS WITH A PH
GREATER THAN 7.
