Carbon Dioxide Flame Extinguisher

Brief Description: 

Gaseous carbon dioxide is poured into a clear walled vessel containing four lit tea candles suspended at varying heights.  The candles are extinguished one at a time from the lowest to the highest.

Purpose/Goal: 

Illustrate the concept of carbon dioxide not being able to support combustion, as well as showing that carbon dioxide is denser than air.

Explanation of Experiment: 

Solid carbon dioxide (dry ice) sublimes at a temperature of -78.5 °C.  At this temperature, it has a density of 1.56 g/L.  The density of oxygen at 25 °C is 1.31 g/L.  As the more dense carbon dioxide is poured into a vessel containing four lit candles suspended at varying heights, the candles are extinguished one at a time from the bottom up.

Materials Preparation: 

Prepare a clear plastic tank by placing four jars and/or beakers of varying capacities inverted so that you have a cascading array.  Place a tea candle on the bottom of each beaker/jar.  Place a number of pieces of dry ice in a plastic pitcher and allow them to stand for ca. ten minutes in order to allow it to fill with carbon dioxide gas.  Have a barbecue lighter ready to ignite the candles.

Presentation: 

Light the candles and slowly pour the carbon dioxide gas into the containment vessel. Point out that the heavy gas can be poured much like a liquid, but it cannot be seen.  The candles will extinguish one by one from the bottom up.

Hazards: 

Handle dry ice with protective gloves.  Keep flammables away from open flames.  Never place dry ice in a sealed container.  Wear appropriate eye protection.

Disposal: 

Allow excess dry ice to sublime.  All other materials may be reused.

Video: 

General Concept:

Type of Reaction:

Primary Reference: 
Bilash, B., Gross, G.R. and Koob, J.K. (2010), A Demo A Day - A Year of Chemical Demonstrations, Flinn Scientific Inc., p.25.