University of Wyoming
Science Posse
20-25 Minute Mini-lesson
Sublimation Supreme: Explorations with Dry Ice
Dave McKenzie
Brief Description of Activity:
• During this activity, students will get to explore the chemistry of dry ice – what is it? Does
it exist as a liquid? What happens when we add hot or cold water to the dry ice? What
happens when we add soap to dry ice? Hand sanitizer? Food coloring? Can we blow up a
balloon using dry ice?
Vocabulary:
• Sublimation: the transition of a substance from the solid phase of matter directly to the
gas phase of matter.
• Melting: the transition of a substance from the solid phase of matter to the liquid phase of
matter.
• Freezing Point: the temperature at which a liquid becomes a solid
Content/Concept Focus:
• Dry ice is made of frozen, compressed carbon dioxide, the same stuff we breathe out out
during respiration.
• At normal atmospheric pressure here on earth, carbon dioxide doesn’t exist in liquid form
– rather it sublimates directly into a gas.
• Carbon dioxide is heaver than air around us; this is why the gas produced in the experiment sinks towards the floor.
• The freezing point of Carbon Dioxide (and thus the temperature of the dry ice) is -109.3
degrees Fahrenheit or -78.5 degrees Celsius.
Components of the Scientific Method / Scientific Inquiry Demonstrated:
• This activity focuses first on observing. Students will observe the dry ice and our experiments with the dry ice using a variety of senses – touch, sight, smell, and hearing.
They will also observe the differences that occur when we change one variable of our experiment – for example, adding hot water instead of cold water to the dry ice.
• This activity will also focus on raising questions; students are encouraged to pose questions and explanations throughout the mini-lesson.
• Peripherally (though not necessarily explicitly) students will observe the scientific
method in action as we change one variable at a time (the temperature of the water for
example) and then observe the results and try to draw conclusions.
Requirements:
Space Requirements: This activity requires a table with adequate space around it for 10-15 students to stand as well as easy and quick access to water and a drain.
Materials/Equipment Needed from the School: A table and water source.
Materials Provided by the Science Posse: All supplies needed for the mini-lesson as well as
coverings for the table and floor.
Extra Considerations: Dry ice is a substance that cannot be handled with bare skin, thus the
graduate fellow will be sure to caution students not to touch anything at the station unless they
are given the ok. The graduate fellow will also model appropriate safety behavior with proper
skin and eye protection. This mini-lesson uses water, soap, and food coloring so does have the
potential for messiness.
This project was developed with support from
the National Science Foundation (G-K12 Project # 0841298),
the School of Energy Resources and
the University of Wyoming.