Making Solid Rocket Fuel in the Lab

Introduction: Making Solid Rocket Fuel in the Lab

Music: Kevin MacLeod Once used as solid rocket fuel, because the reaction requires no oxygen. Sulfur and zinc react vigorously. The reaction with zinc produces flame and a near explosion. Sparks fly and smoke billows in this dramatic chemical demonstration. Please do not try this one at home.

Zinc is a bluish-white metal used to galvanize iron, and is also found in alloys, batteries, and rubber. Sulfur is a yellow, brittle nonmetal; it can also be found in a powered form. Zinc and sulfur react with each other violently to produce zinc sulfide; the reaction is accompanied by a vigorous evolution of gas, heat, and light:

Zn(s) + S(s) ——> ZnS(s) [one of the easier
chemical equations
to balance!]

The products of the reaction also include small amounts of zinc oxide (ZnO) and sulfur dioxide (SO2).

!!! Hazards !!!

This reaction produces a great deal of heat energy; clear the area of flammable materials.

This reaction must be performed in a fume hood or some open, well-ventilated area. If you do this in a fume hood, be prepared to spend some time wiping zinc sulfide powder off all of the surfaces in the hood.

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    33 Discussions

    I want to mix (zinc and sulfur) with Sbrto or acetone or alcohol does have the power to raise more or not? plz answer

    We used to have an informal rocket club back in 1963 to 1968. Used a book on Amateur Rocketry. First were small. No nozzle. Tube with aluminum foil soldered in the end. No car so we used bicycles to get to beach at night. Used electrical conduit. Rockets kept blowing up. Destroyed launch ramp. Changed to seamless stainless tube. Made fuel cells. Card board tube with tissue paper glued on each end. Each cell was about one to two inches long. Packed with Zinc and Sulfur. About two dozen cells per rocket. Wow quite dramatic launches. My physics teacher had a surplus business. Gave us 300 pounds of navy zinc powder. Sometimes called gray lead. Now be built one six feet tall and four inches across. Paid machinist to make nozzle. What a rocket. Designed altitude 40,000 feet. Never saw it again. Zinc and sulfur rockets have a violent acceleration. Fuel burns in seconds. Instrumentation destroyed by g forces.

    Correction on weight. The five foot rocket weighed 70 pounds fueled and 12 pounds empty.

    I have made several zinc and sulfur rockets and this propellant combination is not shock sensitive and very safe to use. Mix 2 pounds of zinc dust with one pound of flowers of sulfur. For a very fast reaction screen the zinc dust through a 400 mesh screen. I just mixed the two ingredients in a dry state but acetone could also be used if a binder of some sort was used. My rockets used a 2" O.D. seamless steel tube with an .125" wall thickness and a converging/diverging nozzle with about a 3/4" diameter throat. Make the nozzle from copper or brass to improve heat transfer in the nozzle and eliminate erosion just downstream of the throat. Compress the fuel/oxidizer mixture in the tube with aluminum pressing ram. This will eliminate voids and keep the burning surface area constant (this is what's called an end burner). I fired this design perhaps a dozen times with tube lengths from a foot long to 6 feet long. The burn time seemed to be less than a second regardless of the tube length which tells me this propellant combination has a burn rate proportional to chamber pressure. Not a desirable feature so I would strongly recommend some type of inhibitor to slow down the burn rate. The rocket exhaust is a beautiful supersonic stream much like the solid boosters of the Space Shuttle and the sound is very loud. I have been within 40 feet of the rocket when is was fired in a test stand and threw my arms in front of my to face to block out the heat. My five foot long rocket weighed 24 pounds fueled and 12 pounds empty and went about 1200 feet up. A spectacular show. Good luck.

    would it be possible to make mix zinc and sulfur in boiling water (make a solution, but make it thick) and let it dry in a mould to create a solid piece of fuel? just wondering and if anyone can help with that question that would be great. cheers

    8 replies

    Or, melt the sulfur, mix in the zinc, then stir. Then pour the mixture into water to make plastic sulfur, then squish it into a mold, then let it crystallize.

    zinc is a metal so it doesnt like to mix with water and sulfur doesnt absorb water either , if you tried this, the solids will just simply sink to the bottom of the solution

    That would not be the best idea in my opinion. What you should try is directly adding cold water to the powder mixture until it's a paste, shape it and dry. Or, if the paste is too runny or crumbly, you could try adding a thickener of some sort, like flour. This will make it nice and pliable with the protein compounds in the flour to make it all stick together. I don't think it would hurt the explosive, as long as you let it completely dry before you ignite it.

    Flour itself will burn quite vigorously if spread into dust in the air, so I doubt it would cause burning problems.

    Alright thanks for that mate. If I end up trying it out I'll let you know how it went. Cheers

    you could try adding some dextrin with the water, make it crumbly, then compress it into a mould, thats what I do with BP engines... anyone think i should make a Instructable on it?

    wow. just wow...in a science camp we made thermite! it was very bright...