What happens when potassium iodide is added to starch solution?
If an aqueous solution of Potassium iodide is added to a solution of starch, there is no immediate reaction. This is often the initial step in making a test paper or solution to detect the presence of oxidizing agents such as Chlorine, Nitrous acid or Hydrogen peroxide. The test paper will turn a deep blue to blue-black color for a positive reaction. When the Iodide anion (I-) is oxidized, it forms diatomic Iodine (I2). The Iodine the reacts with additional Iodide to form tri-iodide (I3-).
