Sodium bisulfate, also known as sodium hydrogen sulfate, is the

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

salt of the

bisulfate The sulfate or sulphate ion is a Polyatomic ion, polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salt (chemistry), ...

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

, with the molecular formula NaHSO₄. Sodium bisulfate is an

acid salt An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen cation, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid. The first category of acids are the ...

formed by partial neutralization of

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...

by an equivalent of sodium base, typically in the form of either

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base (chemistry), ...

(lye) or

sodium chloride Sodium chloride , commonly known as Salt#Edible salt, edible salt, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. It is transparent or translucent, brittle, hygroscopic, and occurs a ...

(table salt). It is a dry granular product that can be safely shipped and stored. The

anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achie ...

form is

hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption (chemistry), absorption or adsorption from the surrounding Natural environment, environment, which is usually at normal or room temperature. If water mol ...

. Solutions of sodium bisulfate are acidic, with a 1M solution having a pH of slightly below 1.

Production

Sodium bisulfate is produced as an intermediate in the

Mannheim process The Mannheim process is an industrial process for the production of hydrogen chloride and sodium sulfate from sulfuric acid and sodium chloride Sodium chloride , commonly known as Salt#Edible salt, edible salt, is an ionic compound with th ...

, an industrial process involving the reaction of

and

: : The process for the formation of sodium bisulfate is highly exothermic. 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, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungency, pungent smell. It is classified as a acid strength, strong acid. It is ...

as a useful coproduct of the reaction. Sodium bisulfate can be generated as a byproduct of the production of many other mineral acids via the reaction of their sodium salts with an excess of

: :NaX + H₂SO₄ → NaHSO₄ + HX ( X⁻ = CN⁻, NO₃⁻, ClO₄⁻) The acids HX produced have a lower boiling point than the reactants and are separated from the reaction mixture by distillation.

Chemical reactions

Hydrated sodium bisulfate dehydrates at at which point it separates from the water molecule attached to it. Once cooled again, it is freshly hygroscopic. Heating sodium bisulfate to produces

sodium pyrosulfate Sodium pyrosulfate is an inorganic compound with the chemical formula of Na2S2O7. It is a colorless salt. It hydrolyses in water to form sodium bisulfate with a chemical formula of NaHSO4 which has a pH of around 1. Preparation Sodium pyrosulfat ...

, another colorless salt: :

Uses

Sodium bisulfate is used primarily to lower pH. It is also used in metal finishing,

cleaning product Cleaning agents or hard-surface cleaners are substances (usually liquids, powders, sprays, or granules) used to remove dirt, including dust, stains, foul odors, and clutter on surfaces. Purposes of cleaning agents include health, beauty, removing ...

s, and to lower the pH of water for effective chlorination in swimming pools and hot tubs. Sodium bisulfate is also AAFCO approved as a general-use feed additive, including use in

poultry feed Poultry feed is food for farm poultry, including chickens, ducks, geese and other domestic birds. Before the twentieth century, poultry were mostly kept on general farms, and foraged for much of their feed, eating insects, grain spilled by cattl ...

and companion animal food. It is used as a urine acidifier to reduce urinary stones in cats. It is highly toxic to certain

echinoderm An echinoderm () is any animal of the phylum Echinodermata (), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". While bilaterally symmetrical as ...

s, but fairly harmless to most other life forms; so it is used in controlling outbreaks of

crown-of-thorns starfish The crown-of-thorns starfish (frequently abbreviated to COTS), ''Acanthaster planci'', is a large starfish that preys upon hard, or stony, coral polyps (Scleractinia). The crown-of-thorns starfish receives its name from venomous thornlike spines ...

. Sodium bisulfate was the primary active ingredient in the toilet bowl cleaners Vanish and

Sani-Flush Sani-Flush was an American brand of crystal toilet bowl cleaner formerly produced by Reckitt Benckiser. Its main ingredient was sodium bisulfate; it also contained sodium carbonate as well as sodium lauryl sulfate, talc, sodium chloride, fragrance ...

, both now discontinued. In the textiles industry, it is sometimes applied to

velvet Velvet is a type of woven fabric with a dense, even pile (textile), pile that gives it a distinctive soft feel. Historically, velvet was typically made from silk. Modern velvet can be made from silk, linen, cotton, wool, synthetic fibers, silk ...

cloth made with a silk backing and a pile of cellulose-based fiber (rayon, cotton, hemp, etc.) to create "burnout velvet": the sodium bisulfate, when applied to such a fabric and heated, causes the cellulose-based fibers to become brittle and flake away, leaving burned-out areas in the finished material, usually in attractive patterns. Sodium bisulfate is the active ingredient in some granular

poultry litter In agriculture, poultry litter or broiler litter is a mixture of poultry excreta, spilled feed, feathers, and material used as bedding in poultry operations. This term is also used to refer to unused bedding materials. Poultry litter is used in ...

treatments used to control ammonia. Sodium bisulfate has also been shown to significantly reduce the concentration of ''Campylobacter'' and ''Salmonella'' in chicken houses. Sodium bisulfate is sometimes used as the active ingredient in flocculant tablets, a step in soil and water quality test kits.

In food

Sodium bisulfate is used as a

food additive Food additives are substances added to food to preserve flavor or enhance taste, appearance, or other sensory qualities. Some additives, such as vinegar ( pickling), salt ( salting), smoke ( smoking) and sugar ( crystallization), have been used f ...

to leaven cake mixes (make them rise) as well as being used in meat and poultry processing and most recently in browning prevention of fresh-cut produce. Sodium bisulfate is considered

generally recognized as safe Generally recognized as safe (GRAS) is a United States Food and Drug Administration (FDA) designation that a chemical or substance added to food is considered safe by experts under the conditions of its intended use. An ingredient with a GRAS d ...

(GRAS) by the FDA and has been named to the

EPA Safer Choice The U.S. Environmental Protection Agency’s (EPA's) Safer Choice label, previously known as the Design for the Environment (DfE) label, helps consumers and commercial buyers identify and select products with safer chemical ingredients, without ...

Safer Chemicals Ingredients List. The food-grade product also meets the requirements set out in the

Food Chemicals Codex The Food Chemicals Codex (FCC) is a collection of internationally recognized standards for the purity and identity of food ingredients. Scope The FCC features more than 1,250 monographs, including food-grade chemicals, processing aids, foods (suc ...

. It is denoted by

E number E numbers, short for Europe numbers, are codes for substances used as food additives, including those found naturally in many foods, such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly ...

E514ii in the EU and is also approved for use in Australia, New Zealand, Canada, and Mexico. where it is listed as additive 514. Food grade sodium bisulfate is used in a variety of food products, including beverages, dressings, sauces, and fillings. It has many synonyms including bisulfate of soda, sodium acid sulfate, mono sodium hydrogen sulfate, sodium hydrogen sulfate, sodium hydrosulfate, and sulfuric acid sodium salt (1:1). Sodium bisulfate lowers the pH without creating a sour taste, and has been used in the place of citric, malic, or phosphoric acids that are commercially available, and it can also be used as an anti-browning agent.

Notes

The "bi" refers to the presence of the hydrogen.

References

External links

Food Chemicals Codex
{{Sulfates Sulfates Sodium compounds Acid salts Photographic chemicals Cleaning products Food additives