MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY
Iodine clock reaction. At left, a clear solution of potassium iodide, sodium thiosulfate, and starch is added to a clear solution of hydrogen peroxide with sulfuric acid in the conical flask. A digital clock is started. At right, a chemical equilibrium has been reached when the solution turns a dark blue/black. The digital timer is stopped and the reaction time is read off.
Model release not required. Property release not required.