Ammonia vs. Ammonium – what is the difference between these . . . - Hach Ammonia and ammonium are different forms of nitrogen The major factor that determines the proportion of ammonia to ammonium in water is pH The activity of the ammonia is also influenced by ionic strength and temperature It is important to remember as un‐ionized NH 3 can be harmful to aquatic organisms, while ionized ammonium is basically harmless The chemical equation that drives the
Chemistry Explained: Hardness - Hach Traditionally, either murexide indicator (ammonium purpurate) or Eriochrome Blue-Black R indicator is followed by titration with EDTA CalVer 2 Calcium Indicator has been developed by Hach to replace these indicators CalVer 2 (hydroxy naphthol blue) is more sensitive and has a sharper end point color change
Chemistry Explained: Silica - Hach Some forms of silica (usually polymeric) will not react with ammonium molybdate and must be digested with sodium bicarbonate to be converted to a reactive form Silicic acid reacts with water and hydrates as follows: H2SiO3 + 3H2O → H8SiO6 This hydrated silicic acid reacts with molybdate in the presence of acids to form silicomolybdic acid
Chemistry Explained: Chemical Oxygen Demand (COD) - Hach The final amount of dichromate is most commonly determined by direct titration using ferrous ammonium sulfate as the titrant and “ferroin” (1,10-phenanthroline ferrous sulfate) as the indicator