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

sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...

salt of the

bisulfate The sulfate or sulphate ion is a 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 salts of sulfuric acid and many a ...

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 convent ...

, with the molecular formula NaHSO₄. Sodium bisulfate is an

acid salt Acid salts are a class of salts that produce an acidic solution after being dissolved in a solvent. Its formation as a substance has a greater electrical conductivity than that of the pure solvent. An acidic solution formed by acid salt is made duri ...

formed by partial neutralization of

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

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 NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alkali ...

(lye) or

sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35.45 g ...

(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 or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance ...

. Solutions of sodium bisulfate are acidic, with a 1M solution having a pH of around 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. The Mannheim furnace is also used to produce potassium sulfate from potassium chloride. The Mannheim ...

, an industrial process involving the reaction of

and

: :NaCl + H₂SO₄ → HCl + NaHSO₄ This step 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, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

as a useful coproduct of the reaction. Although not of commercial interest, 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. Preparation Sodium pyrosulfate is obtained by the dehydration of sodium bisulfate: : 2 NaHSO4 → Na2S2O7 + H2O Temperatures above 460&nbs ...

, another colorless salt: :2 NaHSO₄ → Na₂S₂O₇ + H₂O

Uses

Sodium bisulfate is used primarily to lower pH. it also is 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, bad smells, 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 member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea ...

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 thorn-like spine ...

. Sodium bisulfate was the primary active ingredient in the toilet bowl cleaners Vanish and Sani-Flush, both now discontinued. In the textiles industry, it is sometimes applied to

velvet Weave details visible on a purple-colored velvet fabric Velvet is a type of woven tufted fabric in which the cut threads are evenly distributed, with a short pile, giving it a distinctive soft feel. By extension, the word ''velvety'' means ...

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 have been used for centuries as part of an effort to preserve food, for example vinegar (pickling), salt (salt ...

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 (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 s ...

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 ("E" stands for "Europe") 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 is considered natural by the Grocery Manufacturers Association (GMA) since it is made from minerals. However, all commercially available sodium bisulfate is produced from

synthesized from elemental sulfur via the

contact process The contact process is the current method of producing sulfuric acid in the high concentrations needed for industrial processes. Platinum was originally used as the catalyst for this reaction; however, as it is susceptible to reacting with arsenic ...

. 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

References

External links

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