My Automotive technology class is building a mini wind tunnel. The project is complete but we can't figure out a substance that gives off the vapor trail but still is eviormentaly safe and does not conflict to fire marshall's or smoke ditectors or sprinklers. If anyone has any ideas it would be greatly appriciated

Go get some dry ice and put it in some water. It will give off a fog of water vapor which will be very easy to see.

My Automotive technology class is building a mini wind tunnel. The project is complete but we can't figure out a substance that gives off the vapor trail but still is eviormentaly safe and does not conflict to fire marshall's or smoke ditectors or sprinklers. If anyone has any ideas it would be greatly appriciated

Take two little plastic caps. One cap should be filled with 1 ml of conc. hydrochloric acid and the other cap with ammonia solution. Put them next to each other or even better, put the hydrochloric acid cap just behind the ammonia cap, such that the ammonia vapor blows over the hydrochloric acid. This gives a LOT of white smoke, which is totally safe and you probably will have some excess ammonia vapor (this is released somewhat quicker than HCl vapor). Ammonium chloride is non-toxic (in fact, it is used in certain sweets, called salmiac) and ammonia also is not toxic in these amounts.

 

You have to be careful though that the caps cannot tumble and that their contents is spilled on the device to be tested in the wind tunnel. Conc. hydrochloric acid is very corrosive, especially towards metals.