text: From the above stoichiometric equations, we can find that:
  :1 mole of O → 2 moles of MnO(OH) → 2 mole of I → 4 mole of 
  Therefore, after determining the number of moles of iodine produced, we can work out the number of moles of oxygen molecules present in the original water sample. The oxygen content is usually presented in milligrams per liter (mg/L).