Build Comets in Classroom using Dry Ice and Blow Dryer

[nmsurobert]

i wasnt sure where to post this question.
I want to build "comets" in my class room using dry ice. I am sure a few of you have seen this demo before. however, i want to use a blow dryer to warm it and to also create a stream of air so we can see the "tail" of the comet. I am also hoping that the heat from the dryer will create little jets off our comets.
may seem like a silly question or concern, but is there anything i need to worry about? its not going to explode or ignite, is it?

 

[.Scott]

It won't ignite. It can't really explode, but the CO2 could jettison a fragment of H2O ice, so there's a potential eye hazard.

 

[nmsurobert]

ah ok. i didnt think about flying debris haha .maybe ill just use a fan.

 

[mjc123]

Maybe obvious, but:
Dry ice is very cold. Handle with gloves or tongs.
Dry ice gives off gaseous CO₂, which is an asphyxiant. Make sure the room is well ventilated.

 

[.Scott]

ah ok. i didnt think about flying debris haha .maybe ill just use a fan.

Pass out goggles. They should be handy in a science class.

 

[BillTre]

A visible "tail" may depend on the relative humidity.

If you want little jets, you might want to pulverized your dry ice, mix it with something else of a different melting point (water?) and then refreeze it in a ball or lump (perhaps in an ice cube tray). The jet may result from sublimation from one site but not neighboring areas.

Doing your presentation in the proper lighting conditions will help in visualization.
Dark background, dark room, bright light from the side facing the observers.