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.

Experiment decode messages with a red filter

Decode messages with a red filter

Do you want to send secret messages to your friends, without anyone else being able to read it? Or even send a secret invitation to a lover? Play with light and color transmission to hide your messages. It’s your turn to play! […]


The color decomposition of your markers

The primary colors are cyan, yellow and magenta. Three colors from which all others derive. One way to find out what the color of the felt-tip pens is made of is to play with water, a coffee filter and use the principle of capillary action. […]


A treasure map with invisible ink

Invisible ink is very useful for drawing treasure maps or writing secret messages. Only those who know chemistry will find a way to reveal your message. Let’s use onion juice to prepare the invisible ink. […]

Curiokids, official partner of