Inflate a balloon with lemon.

Have you noticed that some fruit juices are more acidic than others? To find out if the chosen fruit is acidic, there is a very simple way to find out by carrying out a surprising chemical reaction with baking soda. If your fruit juice is acidic, it will inflate a balloon all by itself and without effort.

You will need:

From 7 years old

Difficulty : medium

Let's experiment

Gather everything you need.

Pour two tablespoons of baking soda into your (clean) plastic bottle.

Squeeze and collect the lemon juice in a glass

Pour it into a container with a spout.

Pour the lemon juice into the bottle.

And immediately cap the neck with a balloon.

Watch what happens to your balloon.

Understand the experiment

Your balloon stands up on its own and inflates.

Upon contact with lemon juice, you will see lots of bubbles appearing in the bottle. These same bubbles that straighten up your balloon and inflate it. In your bottle, there is an acid-base reaction. Baking is the base that reacts with the citric acid present in lemon juice. As a result of this reaction, carbon dioxide is produced, the famous CO2.

This reaction proves that there is an acid in lemon juice.


Ready to take the challenge ?

What if you tested different fruit juices to find out which one contains the most of acid? To complete your challenge like a true scientist, you need to put the same amount of baking soda each time. So weigh this amount with your scale. Likewise, for fruit juice, add the same volume each time. Use a measuring jar to help you.

Did you know?

The chemistry of cakes

When you make a cake with baking powder, the same reaction happens. The baking powder already contains a bit of citric acid which reacts with the baking soda. It is thanks to this reaction that your dough “rises”. In other words, it swells because carbon dioxide is released during the reaction and remains trapped in the cake batter. You won’t make your cakes the same way now.


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