Sodium bisulfate

Sodium bisulfate
IUPAC name Sodium hydrogen sulfate
Other names Sodium acid sulfate Bisulfate of soda
Identifiers
CAS number	7681-38-1 Y, 10034-88-5 (monohydrate)
PubChem	7681-38-1
EC number	231-665-7
RTECS number	VZ1860000
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) 1.8 g/cm3 (monohydrate)
Melting point	58.5°C (monohydrate) 315°C (anhydrous)
Boiling point	decomposes to Na2S2O7 (+ H2O) at 315°C
Solubility in water	50 g/100 mL (0°C) 100 g/100 mL (100°C)
Solubility	insoluble in ammonia; decomposed by alcohol
Acidity (pKa)	1.99
Structure
Crystal structure	triclinic (anhydrous) monoclinic (monohydrate)
Hazards
MSDS	External MSDS
EU Index	Corrosive (C)
R-phrases	R34 R37 R41
S-phrases	S26 S36 S37 S39 S45
NFPA 704	0 1 1
Flash point	Non-flammable
Related compounds
Other anions	Sodium sulfate
Other cations	Potassium bisulfate
Y bisulfate (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Sodium bisulfate, also known as sodium hydrogen sulfate (NaHSO₄), is an acid salt. It is a dry granular product that can be safely shipped and stored. The anhydrous form is hygroscopic. Solutions of sodium bisulfate are acidic, with a 1M solution having a pH of < 1.

One production 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 coproduct of the reaction.

There are only two producers in the USA: Jones-Hamilton Co. 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.

Uses

Sodium bisulfate is used primarily to lower pH. For technical grade applications it is used in metal finishing, cleaning products, and to lower the pH of water for effective chlorination, including swimming pools. Sodium bisulfate is also AAFCO approved as a general use feed additive, including companion animal food. It is used as a urine acidifier to reduce urinary stones in cats. Sodium bisulfate is considered GRAS (Generally Recognized As Safe) by FDA^[1] and meets their definition of a natural product. The food grade product meets the requirements set out in the Food Chemicals Codex (FCC). It is denoted by E number E514ii in the EU. Food Grade sodium bisulfate is used in a variety of food products, including beverages, dressings, sauces, and fillings. It is also widely used in meat and poultry processing and most recently in browning prevention of fresh cut produce.

In jewelry making, sodium bisulfate is the primary ingredient used in many pickling solutions to remove the oxidation layer from surfaces, which occurs after heating.^[2]

Highly toxic to at least some echinoderms but fairly harmless to most other lifeforms, sodium bisulfate is used in controlling outbreaks of crown-of-thorns starfish.

References

1. ^ FDA GRAS Notice
2. ^ Fisch, Arline M. (2003), Textile Techniques in Metal: For Jewelers, Textile Artists & Sculptors, Lark Books, p. 32, ISBN 9781579905149, http://books.google.com/books?id=4eFNLNSDNZgC&pg=PA32. 

Further reading

• AAFCO Official publication
• U of Illinois Research
• Food Chemicals Codex
• Browning Inhibitor Study