What does the red cabbage juice color lab experiment test?

It tests one variable: acid or base added. The idea is that red cabbage juice turns pink with acid and blue-green with baking soda.

20-minute experiment

Red cabbage juice color lab

A rainbow from one vegetable.

The idea

Red cabbage juice turns pink with acid and blue-green with baking soda.

The one thing you change: Acid or base added

You need

Red cabbage
Hot water
Three clear cups
Vinegar
Baking soda
A spoon

Steps

Chop the cabbage and pour the hot water over it. Steep for 10 minutes and strain it.
Pour a little purple juice into each cup.
Add vinegar to one cup, baking soda to another, and leave the third plain. Use open cups, never a sealed bottle, since vinegar and baking soda fizz and build pressure. None of these are for drinking.

What you should find

The vinegar cup turns pink, the baking soda cup turns blue-green, and the plain cup stays purple.

From the app

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The science behind it

Red cabbage and pH

Red cabbage is full of anthocyanin, a pigment that changes color with pH. It's pink-red in acid like vinegar or lemon juice, purple in plain water, and…

Read the explainer

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