Friday, 7 February 2014

Magic In Your Kitchen!

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! 


Next, try doing the same with soap solution in a separate container. Add red cabbage juice to it. Notice how the liquid turns to bluish-green, indicating that the soap solution is alkaline. 


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.

Did you know that plants that have colours have pigments in them? Some plants' pigments can react with acid and alkaline and will change colour accordingly. There are many other plants that can be a natural pH indicator too. Next you can try making natural pH indicators using dragon fruit, black berries, grapes and hibiscus too!  

You can also try this at Petrosains and have fun with our current theme, Nature's Kingdom!

Posted by Ayu
Learning Specialist, Petrosains

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