| Sodium bisulfate | |
|---|---|
 |
|
| Other names | sodium bisulfate sodium acid sulfate bisulfate of soda |
| Identifiers | |
| CAS number | 7681-38-1 |
| Properties | |
| Molecular formula | NaHSO4 |
| Molar mass | 120.06 g/mol (anhydrous) 138.07 g/mol (monohydrate) |
| Appearance | white solid |
| Density | 2.742 g/cm3 (anhydrous) |
| Melting point |
58.5°C (monohydrate) |
| Boiling point |
decomposes to Na2S2O7 |
| Solubility in other solvents | 50 g / 100 ml (0°C) (of anhydrous) 100 g / 100ml (100°C) (of anhydrous) |
| Acidity (pKa) | 1.9 |
| Structure | |
| Crystal structure | triclinic (anhydrous) monoclinic (monohydrate) |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references |
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Sodium bisulfate, also sodium hydrogen sulfate, has the chemical formula NaHSO4. The anhydrous form is hygroscopic. Its melting point is poorly defined because it begins to decompose into sodium pyrosulfate and water before it reaches its melting points.
Solutions of sodium bisulfate are acid, with a 1M solution having pH of 1.4. In some applications, such solutions can be used instead of sulfuric acid solution. For example, from a solution of sodium bisulfate and sodium acetate it is possible to distill acetic acid. Sodium bisulfate solutions will also liberate CO2 from most carbonates.
Sodium bisulfate behaves, to some degree, as if it were a complex of sodium sulfate with sulfuric acid. This is evident if either the anhydrous form or the monohydrate come in contact with ethanol, which causes them to separate into those two components.[1]
Sodium bisulfate is produced by two methods. One method involves mixing stoichiometric quantities of sodium hydroxide and sulfuric acid which react to form sodium bisulfate and water.
NaOH + H2SO4 → NaHSO4 + H2O
A second production method involves reacting sodium chloride (salt) and sulfuric acid at elevated temperatures to produce sodium bisulfate and hydrogen chloride gas.
NaCl + H2SO4 → NaHSO4 + HCl
The liquid sodium bisulfate is sprayed and cooled so that it forms a solid bead. The hydrogen chloride gas is dissolved in water to produce hydrochloric acid as a useful byproduct of the reaction.
There are only two producers in the USA, Jones Hamilton Company, uses the sulfuric acid/sodium chloride process, which produces the anhydrous form. Jost Chemical uses the sodium hydroxide/sulfuric acid method, which produces the monohydrate.