Education Science

This awesome little chemical machine is from Mr. Kent’s chemistry page. Ice is laid in a Pyrex dish over a layer of calcium carbide. As the ice melts, the liquid water reacts with the carbide to produce acetylene gas, which of course is highly flammable. A match starts it off, and then it burns continuously on its own. My first thought was that the system could rapidly spiral out of control–more heat melts more water makes more gas makes even more heat. But it’s limited by the amount of oxygen that can get down into the pan, I think. My second thought was that maybe a bit of sodium metal down there with the carbide could make the process self-igniting…. (For God’s sake, no one try that.)

8 thoughts on “Flammable ice

  1. It is my understanding that after the company was sold, the new owners no longer made Pyrex from borosilicate (SP) glass, but instead make it from regular soda ash glass. So it is NOT safe to use it in this fashion, combining freezing
    temps to boiling temps. Ok to go from room temps to the oven, but not safe to go from the freezer to the oven.

    Be sure a and wear eye protection!

  2. Well, it is MY understanding, from having worked in a lab for 10 of the last 12 years, that Corning/Pyrex LABORATORY glassware is still borosilicate. World Kitchen “Pyrex” for kitchen/home use is soda-ash since the sale of that division.

  3. If one were to re-create this experiment, do you have any advice on the ratios of Calcium Carbide to ice that should be used? I wouldn’t want to add too much and risk fire, but I would like it to look impressive. Also, what grade of Calcium Carbide do you recommend?

    To Bill and Wilson…What is the risk of using soda ash Pyrex rather than borosilicate? Is it more likely to break under the high heat? I don’t suppose it would react with the chemicals, and I wouldn’t intend on using it again for food. I’ve read that sand should be used to put out this reaction, but is there a problem with the standard A/B/C fire extinguisher?

    Since Calcium Carbonate seems to be only available in 10+ lb batches, how would you recommend storing this chemical to ensure it stays potent and dry?

    Thanks for the advice, and for the great video.

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I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I am a long-time contributor to MAKE magazine and makezine.com. My work has also appeared in ReadyMade, c't – Magazin für Computertechnik, and The Wall Street Journal.

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