Equilibria Involving Iodine and Iodide

Because of the reactivity of the halogens and their ability to form a bonds between themselves, a number of inteihalogens of the formula XX (X is the more electronegative halogen and n is an odd number) are known. The general preparative method is by reacting the two halogens under specific conditions. 

The combination of chlorine and iodine in a 1 1 molar ratio produces ICl. 

Using a higher Cl/I ratio, this interhalogen can be prepared in a similar way. 

Add 6 g powdered iodine very slowly to S cm liquid chlorine condensed as above. Allow the temperature to rise slowly when excess chlorine is lost and the yellow orange solid remains. Quickly pack into an ampoule and seal off. 

Add a drop of ICl to 10 cm of chloroform. Run the spectrum of the solution in a 10 mm quartz cell over the range 700-325 nm. Compare the spectrum with those of chlorine and iodine in carbon tetrachloride. Use 0.013 M solution of chlorine and 0.0009 M solution of iodine. 

---