Iodine is prepared both in the laboratory and commercially by adding Cl2(g) to an aqueous solution containing sodium iodide:
2NaI(aq) + Cl2(g) ---> I2(s) + 2NaCl(aq)
(97.1 g I2) / (253.8089 g I2/mol) x (2 mol NaI / 1 mol I2) x (149.8942 g NaI/mol) = 12.7 g NaI.
