 We've placed a one molar solution of potassium chloride in the U2. We've placed inert graphite electrodes in the solution. We'll pass the electric current through the solution. At the cathode, we can reduce either the potassium ion or the water. The water is more easily reduced to form hydrogen ion and hydroxide ion. There's been some phenothaline added to the solution. The cathode compartment will turn pink showing the formation of the hydroxide ion. At the anode compartment, the potassium ion cannot be oxidized. The water can be oxidized or the chloride ion can be oxidized. Even though the chloride ion has a more negative oxidation than the water, the chloride ion gets oxidized. The chloride ion is a simpler ion and is more rapidly oxidized than the water. We'll see some gas evolved and the solution may turn a light yellow color. We can test for the presence of dissolved chlorine in the anode compartment by adding a few drops of potassium iodide solution. The chlorine oxidizes iodide to iodine, which produces a yellowish solution.