red cabbage ph indicator

Primary School in ChalineTwinning Club

RED CABBAGE PH INDICATOR

Ania & BartekClass 6

THE PURPOSE OF THIS EXPERIMENT IS TO SHOW HOW TO MAKE YOUR OWN PH INDICATOR USING CABBAGE JUICE

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. 

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.

OUR RED CABBAGE JUICE

Set out 5 glasses, side by side.

Fill each glass half full with cabbage juice.

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.

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.

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.

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.

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.

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.

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.

MADE BY: ANIA & BARTEK