Red cabbage indicator
Red cabbage indicator lesson plan
Results In this case of red cabbage indicator the colour will change from purple to red if it is an acid and from purple to green if it is an alkali. A solvent other than water e. We also tested some bleach, which contains the strong alkali sodium hydroxide. Miss Mackie and Mrs deBoeck tested some limescale remover and some oven cleaner. Note: If you use distilled water the indicator will have a reddish purple color and if you use tap water the indicator will have a violet blue color. We put the chopped cabbage into a jug, poured hot water onto it and left it for a few minutes. Let it sit for about 30 minutes to cool down. In an acidic environment it is reddish-pink, in a neutral environment it is purple, and in a basic or alkaline environment it turns bluish-green and even yellow.
Leave to cool for about 30 minutes and the indicator is ready to use. The acid turned the indicator pink, and the alkali turned it blue. Acids and alkalis Acids have a sour taste, like vinegar which contains ethanoic acid and lemons which contain citric acid.
The lower the pH, the more acidic a solution is. Red cabbage contains a pigment called anthocyanin which is what changes colour.
Approximate pH Range. Fill each of the small beakers or containers with 10 mL of indicator.
How does red cabbage indicator work
The limescale remover turned the indicator red and the oven cleaner turned it green. A solvent other than water e. Soap and washing powder are alkaline. Once dry cut the filter paper into strips and dip into test substances. Use a pipette to drop about 20ml of red cabbage indicator into each cup and record the colour the indicator changes to. Drop a couple of indicator ice cubes into each cup. This collection of over practical activities demonstrates a wide range of chemical concepts and processes. Place cups in a saucepan and cover with water. We started by testing vinegar, which is weakly acidic, and sodium bicarbonate, which makes a weak alkaline solution in water. This is because water alone is not acidic or alkaline - we say it is neutral. Tip into a saucepan and pour over boiling water from the kettle. This is a great way to introduce the concept of acids and bases to a child since they can see the color change before their very eyes.
Soap and washing powder are alkaline. It is neither basic or acidic.
based on 9 review