Let's do magic by using something that you can get from your kitchen! But is it really magic or is it science? Science magic tricks look like "magic," but there is a secret behind the special effects. The secret is a scientific principle or concept from maybe chemistry or physics that makes it look like a 'magic' trick. The great thing is these 'magic' tricks can be used to demonstrate or teach a scientific concept like chemistry in a fun way. Here is a science magic trick using 'red cabbage juice' as a natural pH indicator that changes colors according to the acidity and basicity of the solution!
But how do you do it? Just peel off six red cabbage leaves and put them in a blender filled half full with water. Then pour the purplish cabbage liquid through a strainer to filter out all of the big chunks of cabbage. Keep the red cabbage juice in a bottle and store it in a refrigerator.
Red cabbage contains a water-soluble pigment called anthocyanin that changes color when it is mixed with an acid or base. The pigment turns red in acidic environments and turns bluish-green in alkaline environments. In chemistry, pH is a measure of the acidity or basicity of a solution.
Now comes the interesting part! Take a small container and fill it with lemon juice. Add red cabbage juice to the container and notice the colour change to red, which indicates that lemon juice is acidic. Watch the video!
Repeat your experiments! Try it with other solutions like detergents and vinegar. You'll find the answer immediately, as to whether it is acidic or alkaline. Usually, an acid is a substance with a sour taste. It also has a pH value of less than 7. However, an alkaline tastes bitter with a pH greater than 7.
You can also try this at Petrosains and have fun with our current theme, Nature's Kingdom!