Sodium bisulfate
Sodium bisulfate, also known as sodium hydrogen sulfate (NaHSO4), is an acid salt
Acid salt
Acid salt is a somewhat obscure term for a class of salts formed by the partial neutralization of diprotic or polyprotic acids. Because the parent acid is only partially neutralized, one or more replaceable hydrogen atoms remain. Typical acid salts have one or more alkali metal ions as well as one...

. It is a dry granular product that can be safely shipped and stored. The anhydrous
As a general term, a substance is said to be anhydrous if it contains no water. The way of achieving the anhydrous form differs from one substance to another...

 form is hygroscopic
Hygroscopy is the ability of a substance to attract and hold water molecules from the surrounding environment. This is achieved through either absorption or adsorption with the absorbing or adsorbing material becoming physically 'changed,' somewhat, by an increase in volume, stickiness, or other...

. 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
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

 which react to form sodium bisulfate and water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

NaOH + H2SO4 → NaHSO4 + H2O

A second production method involves reacting sodium chloride
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

 (salt) and sulfuric acid at elevated temperatures to produce sodium bisulfate and hydrogen chloride
Hydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...

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
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric 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.


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 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
Pickling (metal)
Tarnision is a metal surface treatment used to remove impurities, such as stains, inorganic contaminants, rust or scale from ferrous metals, copper, and aluminum alloys. A solution called Tarnision liquor, which contains strong acids, is used to remove the surface impurities...

 solutions to remove the oxidation layer from surfaces, which occurs after heating.

Highly toxic to at least some echinoderm
Echinoderms are a phylum of marine animals. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone....

s but fairly harmless to most other lifeforms, sodium bisulfate is used in controlling outbreaks of crown-of-thorns starfish
Crown-of-thorns starfish
The crown-of-thorns starfish is a large nocturnal sea star that preys upon coral polyps. The crown-of-thorns receives its name from venomous thorn-like spines that cover its body. It is endemic to tropical coral reefs in the Red Sea, the Indian Ocean, and the Pacific Ocean...


Further reading

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