RHYS LEWIS & MINH TAN PHAM, AHS, DECD, UNISA / SCIENCE PHOTO LIBRARY RHYS LEWIS & MINH TAN PHAM, AHS, DECD, UNISA / SCIENCE PHOTO LIBRARY
Halloween clock reaction. The clear solution in the beaker turns orange and then black. A solution of soluble starch, sodium metabisulphite and mercury (II) chloride, is poured into a solution of potassium iodide. As the mercury iodide precipitates the solution turns orange. Then as a starch-iodine complex forms turning the solution black.
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