What happens when you drip a sour lemon into purple cabbage juice?
This is magic purple juice, made from a cabbage… watch what it can do. We have a sour lemon and some slippy soap. We are going to drip the sour lemon into the very same purple juice. Now guess… will it turn pink, or will it turn green? Tap your guess, then watch the whole cup swirl and change. This juice is a little color detector — telling you what you poured in!
After you watchWhat happens when you drip a sour lemon into purple cabbage juice?
The short answer
The purple juice is made from red cabbage, and it is a tiny color detector. Sour things like lemon turn it pink, and soapy things turn it green. It is always the same juice — the color is telling you what kind of liquid you poured in.
The whole story
How it works
Cabbage juice has a special purple color helper inside it. When it meets something sour, the helper changes its shape and the juice looks pink. When it meets something soapy, the helper changes a different way and the juice looks green. Same juice, different liquids, different colors.
What people get wrong
Kids often think the juice is just purple paint that stays purple. But it is not paint at all — the very same juice can turn pink in lemon and green in soap, because it is reading the liquid, not coloring it.
Questions kids ask
Is the pink juice and the green juice the same juice?
Yes! It is the exact same purple cabbage juice both times. The lemon made one cup pink and the soap made the other cup green. The juice did not change — it was telling you which liquid was sour and which was soapy.
Can I make this juice at home?
Yes, with a grown-up. You soak red cabbage in warm water until the water turns purple, then pour a little into cups and drip in lemon or soapy water to watch the colors change. Look at the colors, but do not drink the cups once soap is added.
Keep going
What else makes you wonder?
- What other sour or soapy things in your kitchen could you drip in to change the color?
- Do you think other colorful juices, like grape or blueberry, could be color detectors too?