Science At Play: Red Cabbage Juice Indicator - Connecticut Science Center (2024)

FAQs

What is science at play red cabbage juice indicator? ›

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.

Red cabbage contains a chemical called anthocyanin. This pigment is a natural acid-base indicator. It is blue in neutral substances, like plain water. When an acid like lemon juice gets in the water, a reaction makes the indicator molecule change shape and it looks pink.

You can make a DIY pH indicator by boiling red cabbage leaves to extract the juice. Once prepared, this natural pH indicator changes color depending on the acidity or alkalinity of substances it's tested with: Acids turn it pink, bases turn it green and neutral substances keep it reddish-purple.

The dishwasher soap mixture should turn a vivid blue-green because dishwasher soap is very basic, or alkaline.)

Break off the red cabbage leaves and add them to the boiling water. Keep adding leaves until the water is a deep purple, then strain the leaves out and place the cabbage indicator juice in a pitcher. Red cabbage juice changes color to indicate the pH of various everyday items.

Unused red cabbage indicator solution may be stored in a stoppered flask and refrigerated for up to one week.

The behaviour of a natural acid base indicator (red cabbage juice) was tested. The cabbage indicator varied in colour when coming into contact with different solutions. As stated in the hypothesis, the most basic substances turned yellow, neutral substances turned purple and most acidic substances turned red.

The vinegar will turn the cabbage juice red because it is an acid (acetic acid). The baking soda will turn the cabbage juice greenish-yellow because it is a base (sodium bicarbonate).

The cabbage basically contains a pigment molecule called flavin or anthocyanin that changes colour depending on the acidity of the solution. Normally, the purple solution turns red in colour when it combines with something acidic and it turns bluishg-green in colour when it combines with a base.

Red cabbage juices is the best known edible pH indicator in your kitchen but there are many safe fruits, vegetables and flowers that change color in response to acids and bases such as eggplant, beets, blueberries, cherries, onion, raspberry, grape juice, turmeric, and even tomatoes!

What are the results of the red cabbage indicator? ›

Red Cabbage Indicator Colours

The colour of our red cabbage indicator should be dark blue. If the solution is an acid, the colour of the cabbage indicator will change to red or pink, and if it is a base, it will change to green or yellow. If the test solution is neutral, it will continue to be purple or blue.

Add the cabbage and one cup (or 200 mL) of water into the blender. Blend the water and cabbage and then strain the mixture, saving the liquid. Adjust the amount of water accordingly. You will need roughly 5 mL of indicator per test.

By itself, the cabbage liquid is a pretty purple color. Acidic vinegar turns the dye pink, while adding alkaline baking soda turns the dye a blue color. If enough baking soda is added, the blue dye will dry a greenish color.

You can conduct a neutralization experiment using a cabbage juice indicator. First, add an acidic solution such as vinegar or lemon, then juice until a reddish color is obtained. Add baking soda or antacids to make the mixture more neutral.

The red cabbage solution will turn a colourless solution of bleach to light yellow which indicate the bleach is alkaline or basic. This happens because bleach is alkaline.

Purple cabbage juice is a pH indicator, or a substance that changes color when it's mixed with an acid or base. If you add an acid to the cabbage juice, it turns pinkish red. The more red the solution is, the more acidic that substance is. But if you add a base to the cabbage juice, the solution becomes greenish.

When anthocyanin comes in contact with the hydronium ions in an acid it turns pink, and when it comes in contact with the hydroxide ions in a base it turns blue or green. We refer to cabbage juice as a pH indicator because it can tell us if a substance is acidic or basic by changing colour.

Answer: (a) When acidic soil is treated with purple cabbage juice, it will turn red.