Preparation of Sodium Triiodide solution
Details
Sodium Tiiodide has the formula NaI3 . It is a compound with the polyatomic anion of Triiodide = I3 (-) . It contains Iodine in a -1/3 oxidation state. This compound is only stable in solution form. It will decompose if the solution is evaporated. It has a red color in solution.
Requirements
- Sodium Iodide = NaI
- Iodine = I2
- Water
- Beaker
Process
- Take water in a beaker and dissolve NaI in it.
- Slowly add Iodine to it and stir.
- Dissolve Iodine until no more dissolves and make the solution Iodine-saturated. The solution will change to Red color.
- Filter off the solution, if there excess Iodine left.
Observations
Iodine is sparingly soluble in water due to its low polarity, and as it dissolves in water it forms a straw yellow solution. When Iodide ions are present in the solution, the Iodine reacts with them to form Triiodide ions :
I(-) + I2 = I3(-)
The Triiodide ions are soluble in water and dissolve to form a clear red solution. The Triiodide salt cannot be isolated as a solid because as we remove it out of the solution, it decomposes into Iodide ion and elementary Iodine.
I(-) + I2 = I3(-)
The Triiodide ions are soluble in water and dissolve to form a clear red solution. The Triiodide salt cannot be isolated as a solid because as we remove it out of the solution, it decomposes into Iodide ion and elementary Iodine.