Science, Tech, Math › Science Halloween Chemistry Demonstrations Share Flipboard Email Print Science Chemistry Projects & Experiments Basics Chemical Laws Molecules Periodic Table Scientific Method Biochemistry Physical Chemistry 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 January 22, 2020 Try a Halloween chemistry demo. Make a pumpkin carve itself, turn water into blood, or perform an oscillating clock reaction that switches between the Halloween colors of orange and black. 01 of 09 Make Spooky Fog GUSTOIMAGES, Getty Images Make smoke or fog using dry ice, nitrogen, water fog or a glycol. Any of these Halloween chem demos can be used to teach important chemistry concepts relating to phase changes and vapor. 02 of 09 Water into Blood Tetra Images, Getty Images This Halloween color change demonstration is based on an acid-base reaction. This is a good opportunity to discuss how pH indicators work and to identify chemicals that can be used to elicit color changes. 03 of 09 Old Nassau Reaction or Halloween Reaction Siri Stafford, Getty Images The Old Nassau or Halloween reaction is a clock reaction in which the color of a chemical solution changes from orange to black. You can discuss how an oscillating clock is made and what conditions might affect the rate of oscillation. 04 of 09 Dry Ice Crystal Ball Anne Helmenstine This is a dry ice Halloween demonstration in which you make a sort of crystal ball using a bubble solution filled with dry ice. What is neat about this demonstration is that the bubble will achieve a steady-state condition, so you can explain why the bubble reaches size and maintains it rather than popping. 05 of 09 Self-Carving Exploding Pumpkin Allen Wallace, Getty Images Use a historically important chemical reaction to produce acetylene gas. Ignite the gas in a prepared pumpkin to cause the jack-o-lantern to carve itself! 06 of 09 Make Frankenworms Lauri Patterson, Getty Images Turn boring lifeless gummy worms into creepy zombie Frankenworms using a simple chemical reaction. 07 of 09 Bleeding Knife Trick Jonathan Kitchen, Getty Images Here's a chemical reaction that appears to make blood (but really it's a colored iron complex). You treat a knife blade and another object (such as your skin) so that when the two chemicals come into contact "blood" will be produced. 08 of 09 Green Fire Anne Helmenstine There's something eerie about the green fire that just screams "Halloween." Explain how flame tests work then illustrate how metal salts can affect a fire by using a boron compound to produce green flames. Perform the reaction inside a jack-o-lantern for added effect. 09 of 09 Goldenrod "Bleeding" Paper Paul Taylor, Getty Images The dye used to make goldenrod paper is a pH indicator that changes to red or magenta when exposed to a base. If the base is a liquid, it looks as though the paper is bleeding! Goldenrod paper is great anytime you need inexpensive pH paper and perfect for Halloween experiments.