Freezing Flowers With Dry Ice and Alcohol

Materials: ★★★ Requires materials not commonly found in school laboratories
Difficulty: ★★☆ Can be done by science teachers
Safety: ★★★ Only to be attempted with adequate safety procedures and trained staff

Categories: Particles and States of Matter, Dry Ice, Science Shows

Alternative titles: Poor man's Liquid Nitrogen

Summary

A mixture of dry ice and isopropyl alcohol creates a very cold liquid at around -90 °C, which can instantly freeze flowers, candy, or fruit, making them brittle and easy to shatter.

Procedure

Place chunks of dry ice into a pyrex glass or metal container.
Carefully pour in isopropyl alcohol until the dry ice is submerged.
Wait briefly as the liquid temperature rapidly drops.
Using tongs, dip a flower into the mixture for about one minute, then remove and crush it with a hammer, it will shatter like glass.
Repeat with candy or a banana and observe how they harden into stone-like solids.

Links

Dry ice: extreme freeze - MEL Chemistry:

📄 Dry ice: extreme freeze - MEL Science: https://melscience.com/AU-en/articles/dry-ice-extreme-freeze/?srsltid=AfmBOooL37sgOqUDG-IthF9nQBcofxUmAw5VY9UnZEhnX9947l2f73bU

Variations

Test different objects (leaves, fruit, marshmallows) to see how freezing affects their texture.
Use a low-temperature thermometer to follow the temperature as it decreases.

Safety Precautions

This experiment must only be performed under professional supervision.
Always wear goggles, insulated gloves, and a lab coat when handling dry ice and alcohol.
Do not attempt this experiment at home; the extreme cold can cause severe frostbite.
Use only glassware rated for very low temperatures to avoid cracking.
Work in a well-ventilated space, since carbon dioxide gas is released as dry ice sublimates.
Keep flammable materials away - isopropyl alcohol is highly flammable.
Never ingest frozen items made in this mixture.

Questions to Consider

Why does adding isopropyl alcohol allow the mixture to reach colder temperatures than dry ice alone?
How does the rapid freezing change the structure of the flower or fruit?
Why do frozen objects shatter instead of bending like they normally would?
How does this process compare to freezing food with liquid nitrogen?