Red Cabbage Chemistry - Steve Spangler (2024)

FAQs

What is the chemistry behind the red cabbage experiment? ›

Chemistry concepts

Acid-base indicators change color depending on whether they are in acids or bases. Red cabbage leaves contain a substance called anthocyanin that changes color depending on whether mixed with an acid or a base.

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.

Adding universal indicator (or red cabbage solution) to a solution of water and ammonia causes the indicator to turn a beautiful purple (a basic pH of about 11.6). Adding dry ice to this solution results in many color changes as the solution drops from basic down to neutral down to acidic.

Take a few outer leaves of the cabbage and rip it up into smaller pieces and place it into a larger heat resistant bowl. Heat some water to steaming and add it to the cabbage, making sure to cover the cabbage leaves. Allow this to steep for about 30 mins. You'll notice it turn a bluish purple!

Acids will change the color of the cabbage juice to a deep red. Bases will change it to a greenish-yellow Something that has a pH of seven is said to be pH neutral because it is not an acid or a base.

Substances such as lemon juice and vinegar turn the cabbage juice red because they are acidic. Ammonia turns the cabbage juice into a blue/green color because it is a base, a material that tastes bitter and makes an acid neutral.

But red cabbage has higher levels of some types of antioxidants than other types of cabbage. These nutrients are thought to help reduce the risk of health conditions such as cancer, osteoporosis, and heart disease. Red cabbage is particularly rich in anthocyanins, which are a type of flavonoid.

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.

What is responsible for the color purple on red cabbage? The color purple on red cabbage is caused by the presence of anthocyanin.

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

What color does white vinegar turn red cabbage? ›

In the case of white vinegar, the red cabbage juice turns a pink color. This reaction is an excellent demonstration of how substances can act as pH indicators, changing color in response to changes in the acidity or alkalinity of a solution.

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.

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.

CONCLUSION. Red cabbage juice will change its colour when an acidic or alkali solution added into it. For example, when hydrochloric acid is added, the purple coloured red cabbage juice change to red colour and green colour when added ammonia. This shows that red cabbage can act as a natural indicator.

Red cabbage juice contains a natural pH indicator that changes colors depending on the acidity of the solution. The pigment in red cabbage that causes the red color change is called flavin (an anthocyanin). Flavin is a water-soluble pigment also found in apple skins, plums and grapes.

The purple color in red cabbage comes from a class of pigment molecules called anthocyanins. It turns out that anthocyanins are found in flower petals, leaves (it makes them turn red in the fall!) and some fruits such as blueberries.

Purple cabbage, like elderberry juice, is a natural pH indicator. That means that it changes colors depending when you add substances to it of varying pH levels. More acidic substances, like vinegar and lemon juice, turn it more pink. More basic substances, like dish detergent, turn it more blue.

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.