Chile salt petre is a natural source of NaNO3 which also contains NaIO3. The NaIO3 can be used as a source of iodine which produced in the following reactions:
IO−3+3HSO−3⟶I−+3H+3SO2−4 ... (i)
5I−+IO−3+6H+⟶3I2(s)+3H2O ... (ii)
1.0 L of the starting solution which contains 5.80 g NaIO3 per litre is treated with stoichiometric quantity of NaHSO3. A further quantity of the starting solution is added to the reaction mixture to bring about the second reaction.
(Atomic mass of I=127, Na=23, S=32)
___________ equivalents of
IO−3 are present in one mole of
NaIO3 in step (i).