Sodium Bisulfate

What is Sodium Bisulfate?

Sodium Hydrogen Sulfate (NaHSO₄) is also known as Sodium Bisulfate. It is the sodium salt (NaCl) of the bisulphate anion (SO42-). 

Sodium Bisulfate is an acidic salt (acidic solution is produced after salt is dissolved in a solvent)which is produced by partial neutralization of Sulfuric acid (H2SO4)with an equivalent amount of sodium base, basically in the form of sodium hydroxide (NaOH) or sodium chloride (NaCl). The anhydrous is being hygroscopic in nature. The solutions of Sodium Bisulfate are acidic in nature with a pH value of 1 for every 1M solution. It is a white and relatively dry granulated compound. It is corrosive to metals and tissues and also is soluble in water.

What Is The Structure and Type of Bonding in Sodium Bisulfate?

The structure of Sodium Bisulfate molecules are explained in the figure below. It is observed that this compound features an ionic bond (overall transfer of valence electron/electrons between atoms) amongst the negatively charged bisulphate anion (HSO4-) and the positively charged sodium cation (Na+). It has a Sulfur atom bonded with one hydroxyl group (OH- or HO-) and three oxygen atoms.

The accurate mass and the monoisotopic mass of Sodium Bisulfate (NaHSO₄) is 119.9 g/mol. The number of hydrogen bond donor is equal to one and the number of hydrogen bond acceptors equals to four. 

What Are The Properties of Sodium Bisulfate?

Physical Properties: Sodium Bisulfate of NaHSO4 is usually accessible in both monohydrate (hydrate comprising of one mole of water/mole of the compound), NaHSO4.H2O and anhydrous (dry) forms. Anhydrous NaHSO4 is a dry granulated white powder, having a density of 2.74 g/ml with a melting point of 315 °C. Whereas, monohydrate is a white colored granulated solid having density of 1.8 g/ml with a melting point of 59 °C. Monohydrate is considered a dry acid which is appropriate for safe storage and shipping. Its water solubility is 28.5 g/100 ml (25 °C) and 100 g/100 ml (100 °C) respectively

Chemical Properties: Sodium Bisulfate is highly soluble in water. Aqueous solutions of NaHSO4 are highly acidic in nature. Chemically it is an acidic salt, rather than a usual neutral salt. This is due to the replacement of only one acidic proton of the diprotic sulfuric acid. Aggressive reaction takes place with strong oxidizing agents and strong bases. It stays in stable condition under ordinary conditions, but decomposes instantly when contacted to water.

Preparation of Sodium Bisulfate

There are quite a few approaches for obtaining Sodium Bisulfate (NaHSO₄):-

1. The neutralization reaction of an acid with base resulting in the formation of salt and water. NaHSO₄ can be prepared by the reaction of sulfuric acid (H2SO4) and sodium hydroxide (NaOH), but these elements must be reacted in a specific ratio: the acid should be available in plenty as compared to the base. 

H₂SO₄ + NaOH →  NaHSO₄ + H₂O

(Reaction is carried out with concentrated sulfuric acid. Reagents react in the ratio of 1:1.)

By the reaction of 2 moles of NaOH and 1 mole of H₂SO₄, sodium sulfate Na₂SO₄ forms:

H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O

(the protons of H₂SO₄ are completely replaced with Na ions and complete neutralization occurs, the product being normal salt)

2. The reaction of an acid oxide with an alkali (taking oxide in abundance will result in formation of acid salt):

NaOH + SO₃   →     NaHSO₄

If sodium hydroxide (NaOH) is taken in abundance while carrying out this reaction, normal (Na₂SO₄) salt will be formed.

3. The reaction of a normal salt and an acid:

Na₂SO₄ + H₂SO₄    →       2NaHSO₄.

Some acid salts are acquired by hydrolysis (reaction with water, in which the original substance breaks down to form new compounds). NaHSO₄ cannot be acquired from sulphate by hydrolysis, since this salt is originated by the strong base NaOH. Since H₂SO₄ and Na₂SO₄ does not react with water, but only gets dissolved in it. For example, NaHCO₃ is formed by strong base NaOH and the weak acid H₂CO₃.

Uses of Sodium Bisulfate

Sodium Bisulfate falls under the class of chemical compounds known as acid salts. At the time of its production, NaHSO₄ preserves one of the hydrogen ions of a raw material (sulfuric acid), thus obtaining he acidic properties. It is this acidic quality which classifies NaHSO₄ as a general acid for industrial uses. Simultaneously, it is considered as a special acid for few applications because of its purity. NaHSO₄ is dry and granular which is readily soluble in water and commonly used for adjusting pH in many applications.


Sodium bisulfate is commonly used as a preservative, food additive, in meat processing, in dietary supplements and in drugs. It is used as a food additive to make dough rise as well as being used in meat and poultry processing. Recently it is being used in browning prevention of fresh-cut produce. It is also used as a general-use feed additive, including companion animal food. 

Swimming Pool Application

Sodium Bisulfate is used for reducing pH level in swimming pools and spas. NaHSO₄ is the safest product for use in homes, spas and institutional pools. Generally, 1-2 lbs. are applied in a pool of capacity 10,000 gallon which adequately reduces the pH level. After one or two hours the pH is above 7.8, the treatment is repeated until the pH level is between 7.2 and 7.6.

Metal Finishing

NaHSO₄ is the chief component for dry acid bath formulations in metal cleaning. The common formula for most of the acidic bath includes: salts of fluorides (5-10%), NaHSO₄ (90-95%) along with a surfactant (substance which reduces surface tension). The concentration is normally 3 lbs. per gallon of water. At temperatures till 170°F., this bath has the capability to clean copper, brass, steel, nickel, zinc, aluminum, titanium, magnesium and stainless steel. Typically used are for scale removal, pickling, etching andrust removal.


Sodium Bisulfate defends agricultural spray chemicals owing to alkaline hydrolysis in spray solutions. The effectiveness of agricultural pesticides is significantly lessened when added to water having high pH. NaHSO₄ functions mainly well with glyphosate (kills unnecessary grasses) to improve their usefulness. Acidification with Sodium Bisulfate is suggested as a substitute to ammonium sulfate ((NH₄) ₂SO₄) for use with several herbicides.

Water Treatment

Sodium Bisulfate is applied as a descaler in boilers, cooling towers, and also water pipes. Sodium Bisulfate cleans and adjusts pH level. If there is a requirement for waste treatment of an alkaline nature, Sodium Bisulfatehighly is recommended.

Concrete Wash Out

Sodium Bisulfate reduces alkalinity in “wash out” ponds which is formed due to concrete truck cleaning. Concrete companies are potential distributor. Representatives of JonesHamilton Co. technical service can recommend pH adjustments.

Leather Tanning

Sodium Bisulfate acts as an acidifier for leather compounds when combined with quebracho tannin. It is added with fillers and other chemicals for acidifying hides used in shoe sole leather.

What are the safety hazards of Sodium Bisulfate?

Due to its strong acidic nature, sodium bisulfate is very irritating to the eyes and skin. At high concentrations, it can cause serious eye damage upon contact. It can cause severe diarrhoea and vomiting if swallowed and is very toxic in large amounts. Sodium hydrosulfate is a toxic, corrosive and non-combustible compound. Inhaling, swallowing or skin contact causes severe injury or leads to death. Oh heating, it liberates irritating and toxic gases.

FAQ (Frequently Asked Questions)

1. Is sodium  bisulfate  a strong acid?

The aqueous solution of NaHSO4 is highly acidic. It is used for controlling pH level, disinfecting, household products, leather tanning, metal cleaning, swimming pool acidic level and various other applications. Safety hazards/health effects: due to its strong acidic nature, sodium bisulphate is extremely irritating to the skin and eyes.

2. Is sodium bisulfate safe to eat?

Sodium bisulfate (NaHSO4) is very irritating to the skin. It can result in severe eye injury if contact takes place. Also, swallowing of this chemical can cause symptoms of likevomiting, diarrhoea and low blood pressure.

3. What is another name for sodium bisulfate?

Sodium bisulfate also called sodium hydrogen sulfate. It is the sodium salt of the bisulfate anion, with molecular formula NaHSO4.

4. Where is sodium bisulfate found?

Sodium bisulfate is highly acidic in nature, is found in cleaning products like toilet cleaners, dishwashers, etc. It is also used in many industries for adjusting pH level and also in spas, swimming pools, aquarium etc.

5. Is sodium bisulfate toxic?

Sodium bisulfate (NaHSO4) is a dry granulated acid which may be very harmful if swallowed in large amounts.

6. How is Sodium bisulfate made?

Sodium bisulfate is made by the reaction of sulfuric acid (H2SO4) and sodium hydroxide (NaOH) reacted in a certain ratio of 1:1.

H2SO4 + NaOH  →     NaHSO4 + H2O

7. What are the uses of sodium bisulfate?

Sodium bisulfate or NaHSO4 is used for the following things:-

  • Used to lower the pH of water in swimming pools.

  • Used as a catalyst.

  • Used in the water treatment products.

  • Used as a bleaching agent.

  • Used in paints.

  • Used in agricultural chemicals.

  • Used in velvet cloths.

  • Used in the manufacturing of paper products.

  • Used in the chicken house to reduce the concentration of Salmonella.

  • Used in metal finishing.

8. What happens when sodium bisulfate is heated?

2NaHSO4   →    Na2S2O7 + H2O

Heating sodium bisulfate up to a temperature of 250 °C or 482 °F results in the change of NaHSO4 to pyrosulphate (Na2S2O7).