Science, Tech, Math › Science How to Make a Pharaoh's Snake Firework Share Flipboard Email Print Martin Leigh/Getty Images Science Chemistry Physical Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated September 30, 2019 Pharaoh's snakes or Pharaoh's serpents are a type of small firework in which a lighted tablet exudes smoke and ash in a growing column which resembles a snake. The modern version of this firework is the non-toxic black snake. Pharaoh's snakes produce a more spectacular display, but they are toxic so this firework is only produced as a chemistry demonstration. If you have the materials and a fume hood, you can make your own Pharaoh's snakes. Safety First Although Pharaoh's snakes are considered a type of firework, they do not explode or emit sparks. They burn on the ground and release smoky vapors. All aspects of the reaction can be hazardous, including handling the mercury thiocyanate, breathing the smoke or touching the ash column, and contact with the remains of the reaction during clean-up. If you perform this reaction, use appropriate safety precautions for dealing with mercury. Making Pharaoh's Snakes This is an extremely simple firework demonstration. All you need to do is ignite a small pile of mercury(II) thiocyanate, Hg(SCN)2. Mercury thiocyanate is an insoluble white solid which can be purchased as a reagent or can be obtained as a precipitate by reacting mercury(II) chloride or mercury(II) nitrate with potassium thiocyanate. All mercury compounds are toxic, so the demonstration should be performed in a fume hood. Typically the best effect is obtained by forming a depression in a shallow dish full of sand, filling it with mercury(II) thiocyanate, lightly covering the compound, and applying a flame to initiate the reaction. Pharaoh's Snakes Chemical Reaction Igniting mercury(II) thiocyanate causes it to decompose into an insoluble brown mass that is primarily carbon nitride, C3N4. Mercury(II) sulfide and carbon disulfide are also produced. 2Hg(SCN)2 → 2HgS + CS2 + C3N4 Flammable carbon disulfide combusts to carbon(IV) oxide and sulfur(IV) oxide: CS2 + 3O2 → CO2 + 2SO2 The heated C3N4 partially breaks down to form nitrogen gas and dicyan: 2C3N4 → 3(CN)2 + N2 Mercury(II) sulfide reacts with oxygen to form mercury vapor and sulfur dioxide. If the reaction is performed inside a container, you will be able to observe a gray mercury film coating its interior surface. HgS + O2 → Hg + SO2 Disclaimer: Please be advised that the content provided by our website is for EDUCATIONAL PURPOSES ONLY. Fireworks and the chemicals contained within them are dangerous and should always be handled with care and used with common sense. By using this website you acknowledge that ThoughtCo., its parent About, Inc. (a/k/a Dotdash), and IAC/InterActive Corp. shall have no liability for any damages, injuries, or other legal matters caused by your use of fireworks or the knowledge or application of the information on this website. The providers of this content specifically do not condone using fireworks for disruptive, unsafe, illegal, or destructive purposes. You are responsible for following all applicable laws before using or applying the information provided on this website.