 We've placed a solution of potassium iodide in the YouTube. The potassium iodide contains a small amount of phenethylene. Phenethylene is an acid-based indicator that changes from colorless to pink in basic solution. We've placed inert graphite electrodes into the YouTube. We're going to pass a current through the system. The potassium ion is not easily reduced. The water is going to be more easily reduced, so at the cathode we'll see the evolution of hydrogen gas. The solution will turn pink due to the formation of hydroxide ion. At the anode, the iodide ion can be oxidized and is more easily oxidized in the water. So we'll see the solution turn a pale yellow to orange color due to the formation of iodine.