Thermochromism: Mercury(II) Iodide - Temperature Decreases

When the beta form of mercury(II) iodide cools to below the transition temperature of 126°C, it returns to the red/orange alpha form.

When red-orange mercury(II) Iodide (HgI2) is heated, it undergoes a phase transition at 126°C to a pale yellow form. As the heated sample cools, it gradually returns to the original red-orange color.

Credits: 
  • Design and Demonstration
    • George Gilbert Denison University, Granville, OH 43023
  • Video
    • Jerrold J. Jacobsen University of Wisconsin - Madison, Madison, WI 53706
  • Text
    • George Gilbert Denison University, Granville, OH 43023
    • Kelly Houston Jetzer University of Wisconsin - Madison, Madison, WI 53706
    • David Phillips Wabash College, Crawfordsville, IN 47933
    • Nancy S. Gettys University of Wisconsin - Madison, Madison, WI 53706