 In the halogen-halogen single displacement reaction, we will react an aqueous solution of potassium iodide with an aqueous solution of chlorine. The potassium iodide solution is carlos. When we add the aqueous solution of chlorine, the chlorine displaces the iodine from the potassium iodide and we get the formation of a reddish brown solution of iodine. You can test for the fact that iodine is actually being produced by adding a non-poor solvent like hexane. If we shake the solution, the iodine will dissolve in the hexane, producing a characteristic purple color in the hexane layer.