Question

The principal products obtained on heating iodine with cold concentrated caustic soda solution

Answer 1

It depends on whether the NaOH taken is “cold and dilute” or “hot and concentrated”. The reactions involved are as follows:

I2+2NaOH(cold, dil.)→NaI+NaOI+H2O

3I2+6NaOH(hot, conc.)→5NaI+NaIO3+3H2O

The reactions are same for Cl2 and Br2 .