Sodium bisulfate

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Sodium bisulfate
General
Systematic name	sodium hydrogen sulfate
Other names	sodium bisulfate sodium acid sulfate
Molecular formula	NaHSO₄
Molar mass	120.06 g/mol (anhydrous) 138.07 g/mol (monohydrate)
Appearance	white solid
CAS number	[7681-38-1]
Properties
Density	2.742 g/cm³ (anhydrous)
Solubility (water)	50 g / 100 ml (0°C) (of anhydrous) 100 g / 100ml (100°C) (of anhydrous)
Melting point	58.5°C (monohydrate) >315°C (anhydrous) w some decomp
Boiling point	decomposes to Na₂S₂O₇
pK_a (25°C)	1.9
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 disclaimer and references

Sodium bisulfate, also sodium hydrogen sulfate, has the chemical formula NaHSO₄.

1 Production
2 Descriptive Chemistry
3 Uses
4 References
5 External links

[edit] Production

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.

[edit] Descriptive Chemistry

The product of commerce is the monohydrate.

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.

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.

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]