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Ammonium sulfate precipitation is a common method for protein purification by precipitation. As the ionic strength of a solution increases, the solubility of proteins in that solution decreases.
Ammonium iron(II) sulfate, or Mohr's salt, is the inorganic compound with the formula (NH 4) 2 SO 4 ·Fe(SO 4)·6H 2 O.Containing two different cations, Fe 2+ and NH + 4, it is classified as a double salt of ferrous sulfate and ammonium sulfate.
The following chart shows the solubility of various ionic compounds in water at 1 atm pressure and room temperature (approx. 25 °C, 298.15 K). "Soluble" means the ionic compound doesn't precipitate, while "slightly soluble" and "insoluble" mean that a solid will precipitate; "slightly soluble" compounds like calcium sulfate may require heat to precipitate.
Ammonium sulfate is an inorganic salt with a high solubility that disassociates into ammonium (NH + 4) and sulfate (SO 2− 4) in aqueous solutions. [1] Ammonium sulfate is especially useful as a precipitant because it is highly soluble, stabilizes protein structure, has a relatively low density, is readily available, and is relatively inexpensive.
In inorganic chemistry, Fajans' rules, formulated by Kazimierz Fajans in 1923, [1] [2] [3] are used to predict whether a chemical bond will be covalent or ionic, and depend on the charge on the cation and the relative sizes of the cation and anion. They can be summarized in the following table:
Ammonium sulfite can be prepared by the reaction of ammonia with sulfur dioxide in aqueous solution: . 2 NH 3 + SO 2 + H 2 O → (NH 4) 2 SO 3. Ammonium sulfite is produced in gas scrubbers, now obsolete, consisting of ammonium hydroxide to remove sulfur dioxide from emissions from power plants.
After that, all four N−H bonds are equivalent, being polar covalent bonds. The ion has a tetrahedral structure and is isoelectronic with methane and the borohydride anion. In terms of size, the ammonium cation (r ionic = 175 pm) [citation needed] resembles the caesium cation (r ionic = 183 pm). [citation needed]
Binary hydrogen compounds in group 1 are the ionic hydrides (also called saline hydrides) wherein hydrogen is bound electrostatically. Because hydrogen is located somewhat centrally in an electronegative sense, it is necessary for the counterion to be exceptionally electropositive for the hydride to possibly be accurately described as truly behaving ionic.