Sulfamic acid, barium salt

Sulfamic acid and its salts retard the precipitation of barium sulfate and prevent precipitation of silver and mercury salts by alkah. It has been suggested that salts of the type AgNHSO K [15293-60 ] form with elemental metals or salts of mercury, gold, and silver (19). Upon heating such solutions, the metal deposits slowly ia mirror form on the wall of a glass container. Studies of chemical and electrochemical behavior of various metals ia sulfamic acid solutions are described ia Reference 20. 

Since all metal salts of sulfamic acid are water-soluble, this reaction is discernible through the precipitation of barium sulfate if barium ions are introduced. A qualitative test and a gravimetric method for nitrous acid (nitrite) are based on this precipitation. The converse of the nitrite test permits the detection of sulfamic acid by a spot test, provided sulfates and sulfides are absent. 

C. Sulfamates prepared from weak bases form acidic solutions, whereas those prepared from strong bases produce neutral solutions. The pH of 5 wt % solution of ammonium sulfamate is 5.2. Crystals of ammonium sulfamate deliquesce at relative humidity of 70% and higher. Both ammonium sulfamate [7773-06-0] and potassium sulfamate [13823-30-2] hbemte ammonia at elevated temperatures and form the corresponding imidodisulfonate (12). Inorganic sulfamates are quite water-soluble, except for the basic mercury salt. Some relative solubilities of sulfamates at 25°C in 100 g of water are ammonium, 103 g sodium, 106 g magnesium, 119 g calcium, 67 g barium, 34.2 g zinc, 115 g and lead, 218 g. The properties of a number of sulfamates may be found in the literature (see Table 5). 

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