Red Cabbage Juice and Dry Ice Experiment

Dry ice is so amazing for it continues to give off white smoke. Red cabbage will turn into different colors under various PH environments. We combined these two awesome stuff to make an awesome science experiment for kids.

Age: 6+        Time: <20min

 Safety 

1. Adult supervision.

2. Be careful when heating the cabbage.

3. Wear gloves when touching the dry ice.

 Materials List 

• Red cabbage
• Baking soda 10g
• Heater
• Water
• Gauze
• Beaker
• Measuring cylinder
• Knife
• Glass rod
• Gloves

 Instruction 

Step 1/4 – Cut the purple cabbage into small pieces with a knife, then pour into the pot and cook them for about 10 minutes.

Step 2/4 –Filter the red cabbage through the gauze.

Step 3/4 – Pour about the cabbage juice into a measuring cylinder and add the baking soda, stir it up. The color of the red cabbage juice turns from purple to blue.

Step 4/4 – Add a buck of dry ice to the liquid. There will come out a lot of smoke and the color of the liquid will burns back into purple.

 Troubleshooting 

Why the blue color can not change back to purple?

 - Add more dry ice and wait for a longer time.

 Scientific Description 

Red cabbage contains lots of water-soluble pigment, anthocyanins. It may appear red, purple, blue, or even black in different PH. The anthocyanins can also be found in many plants. Like apple, plums, cornflowers, and grapes. Cook the red cabbage in water making the anthocyanins solve into the water. anthocyanins can turn into different colors when in different PH environment.  That is why it is called Red Cabbage Indicator. The baking soda is a kind of alkaline which will make the color of the red cabbage juice turn into blue. The dry ice is the solid-state of carbon dioxide, the solution of which is a kind of acid. The carbon dioxide neutralized the baking soda and when there is no more baking soda in the liquid the blue color turns back into purple.

 Extensions 

You can add some acidic solutions such as vinegar or lemon juice into the red cabbage juice and see what color do you have. Then, add baking soda to turn its color. Check out another red cabbage video,  Red Cabbage Indicator.

Interested in dry ice?    Check our Cool Dry Ice Experiments for Kids to explore more about dry ice. Let's get started with this cool dry ice explore journey now!

 Disposal 

After the dry ice is completely dissolved, pour the liquid into the sink.