Incredible Halloween Dry Ice Techniques...

Key Concepts

• Dry Ice
• Sublimation
• Carbonic Acid
• pH Indicator
• Red Cabbage Juice
• Phenolphthalein

Dry Ice Properties and Handling

Dry ice is a solid form of carbon dioxide that undergoes sublimation, meaning it transitions directly from a solid to a gas without becoming a liquid. This process is responsible for the "spooky bubbling liquids" effect often seen during Halloween.

Key Properties:

• Temperature: Extremely cold, at -110 degrees Fahrenheit (-79 degrees Celsius).
• Handling Precautions: Direct contact can cause frostbite. It is essential to use gloves and a cooler for transport and storage. Children should be supervised to prevent them from touching it.

Dry Ice and Water Temperature Experiment

The rate of sublimation and fog production from dry ice is significantly influenced by the temperature of the surrounding liquid.

Experiment Setup:

• Two containers with the same size piece of dry ice.
• One container filled with cold water.
• One container filled with warm to hot water.

Observations:

• The dry ice in cold water produces less fog.
• The dry ice in warm to hot water produces significantly more fog.

Conclusion: Warm to hot water should always be used when experimenting with dry ice for optimal fog production. For outdoor displays, such as in a pumpkin, changing the water periodically will maintain better fog.

Carbonation and Acidic Properties of Dry Ice

When dry ice is added to a liquid, it forms carbonic acid. This is the same carbon dioxide that gives soda its tingly sensation.

Carbonation Application:

• Dry ice can be used to carbonate beverages.
• Crucial Safety Note: The beverage should never be consumed while dry ice is still present. Allow the dry ice to completely sublimate before drinking.

Acidic Nature:

• Carbon dioxide dissolved in water forms a weak acid (carbonic acid). This property is utilized in the following experiment.

pH Indicator Experiment with Red Cabbage Juice and Phenolphthalein

This experiment demonstrates the acidic properties of dry ice using natural and chemical pH indicators.

Materials:

• Red cabbage juice (made by grinding red cabbage leaves and mixing with water).
• Phenolphthalein (a common chemistry lab indicator).
• Dry ice.

Procedure:

1. Prepare two containers, each containing a pH indicator (one with red cabbage juice, one with phenolphthalein).
2. Add dry ice to both containers.

Observations and Explanations:

• Red Cabbage Juice: This acts as a natural pH indicator.
  • Initially, the red cabbage juice is purple.
  • As the dry ice sublimates and forms carbonic acid, the pH of the liquid decreases.
  • The color change observed is from purple to green, and then to yellow, indicating an acidic environment.
• Phenolphthalein: This is a chemical indicator that is colorless in acidic solutions and pink in alkaline solutions.
  • Initially, the phenolphthalein is pink.
  • As carbonic acid forms, the solution becomes acidic, causing the pink color to disappear.

Outcome: The experiment showcases "Halloween science magic" by visually demonstrating the acidic nature of carbon dioxide from dry ice through dramatic color changes.

Conclusion

This "Halloween spooky science minute" by Steve Spangler highlights the fascinating properties of dry ice, emphasizing its safe handling, its interaction with water temperature for fog production, and its ability to create carbonic acid, which can be used for carbonation and demonstrated through pH indicator experiments. The core takeaway is the accessible and visually engaging science that can be achieved with dry ice for educational and festive purposes.