Sulfuric Acid Properties (23 Facts You Should Know)

Sulfuric acid is an inorganic or mineral acid that is also known as the oil of vitriol in chemistry. Let us explore the different physical and chemical properties of sulfuric acid.

Sulfuric acid has a monoclinic crystal structure with an S-O bond length of 157.4 pm and an O-H bond length of 97pm. Sulfuric acid does not exist in its pure form due to its hygroscopic nature (strong affinity to water vapor) and it absorbs moisture from the air.

Let us focus on the boiling point, melting point, oxidation state, and polarity with detailed explanations.

Sulfuric Acid IUPAC Name

The IUPAC name (International Union of Pure and Applied Chemistry) of sulfuric acid is sulfuric acid itself.

Sulfuric Acid Chemical Formula

Sulfuric acid has the chemical formula H2SO4. In this formula, sulfur is the central atom and it is attached with two OH groups and two oxygen atoms by a single bond and double bond respectively.

Sulfuric Acid CAS Number

Sulfuric acid has the CAS registry number (authentic numeric identifier which can contain upto10 digits) 7664-93-9.

Sulfuric Acid ChemSpider ID

Sulfuric acid has the ChemSpider ID (ChemSpider is a free chemical structure database) 1086.

Sulfuric Acid Chemical Classification

Sulfuric acid can be chemically classified as mineral acid. It is also a very strong acid because the dissociation constant of H2SO4 is very high and it completely ionizes to form sulfate and hydrogen ions.

Sulfuric Acid Molar Mass

The mass of 1-mole sulfuric acid is 98.079 g.

Sulfuric Acid Color

Pure sulfuric acid is colorless or “water-white” oily liquid compound.

Sulfuric Acid Viscosity

Sulfuric acid has a viscosity of 26.7cP (centipoise) at 200 C which indicates that acid is a highly viscous liquid.

Sulfuric Acid Molar Density

The molar density of sulfuric acid is 0.01867 mol/cm3 because it has a density of 1.8302 g/cm3.

Sulfuric Acid Melting Point

Sulfuric acid has a melting point of 10.310 C or 50.560 F.

Sulfuric Acid Boiling Point

The boiling point of sulfuric acid is 3370 C or 6390 F. But when H2SO4 reaches above 3000 C, it decomposes into SO3 and H2O.

Sulfuric Acid state at Room Temperature

At room temperature sulfuric acid is a covalent liquid but it becomes solid below 500 F or 10.310 C.

Sulfuric Acid Ionic/Covalent Bond

There are a total of six covalent bonds present in sulfuric acid. Two double bonds are present between sulfur and two oxygen atoms and other two single bonds are present between sulfur and two OH groups.

sulfuric acid properties
Covalent Bonds in Sulfuric Acid

Sulfuric Acid Ionic/Covalent Radius

The covalent radius of sulfuric acid like any compound cannot be determined as the covalent radius can only be calculated for any single atom.

Sulfuric Acid Electron Configurations

Electron configuration is the distribution of electrons in different atomic or molecular orbitals (s, p, d and f) in any atom. Let us explain the electron configuration of sulfuric acid in detail.

Sulfur and oxygen have almost similar electron configurations due to placing them in the same group which is [Ne] 3s2 3p4 and [He] 2s2 2p4 respectively. The electron configuration of hydrogen is 1s1. Electron configurations can only be shown for any single atom.

Sulfuric Acid Oxidation State

The central atom, sulfur is in a +6-oxidation state in sulfuric acid. Each of the two oxygen atoms is in -2 and each of the two hydrogen atoms is in a +1-oxidation state in sulfuric acid.

Sulfuric Acid Acidity/Alkaline

Sulfuric acid is a very strong inorganic acid with pka values of -2.8 (pka1) and 1.99 (pka2).

Is sulfuric acid odorless?

Sulfuric acid is an odorless liquid compound. But it emits a choking odor when it is heated.

Sulfuric Acid Hydrates

The crystal of H2SO4 contains water molecules and forms hydrates, H2SO4.nH2O in which n can be 1,2,3,4,6,5, and 8 because of its highly hygroscopic nature.

Sulfuric Acid Crystal Structure

Solid sulfuric acid possesses a monoclinic crystal structure with trigonal lattice parameters. The space group of the sulfuric acid crystal is C2/c having formula units of 12 in a cell with the dimensions a= 13.008, b= 7.979, c= 14.881, and β= 101.600.

Sulfuric Acid Polarity and Conductivity

Anhydrous sulfuric acid is a polar compound with a very high dielectric constant of 100. It has also a very high electrical conductivity because it is decomposed through autoprotolysis reaction into H3SO4+ and HSO4. The autoprotolysis constant is 2.7 × 10-4.

Sulfuric Acid Reaction with Acid

Sulfuric acid is itself an acid therefore, it does not react with most acids. In the presence of sulfuric acids, carbonic acid reacts with ethanol groups to form an ester and water. Citric acid is burnt with the help of H2SO4 to destroy various organic compounds and the residue part is called sulfated ash.

Sulfuric Acid Reaction with Base

Sulfuric acid reacts with most of the bases (mainly metal oxide) and produces the corresponding sulfate which is known as a neutralization reaction. For example, copper sulfate is prepared between the reaction of copper oxide (CuO) with H2SO4.

  • CuO (s) + H2SO4 (aq) = CuSO4 (aq) + H2O (l).
  • ZnO (s) + H2SO4 (aq) = ZnSO4 (aq) + H2O (l).

Sulfuric Acid Reaction with Metal

Sulfuric acid reacts with metals (Fe, Al, Zn, Mn, Mg, and Ni) through a single displacement reaction.

  • Fe+ 2H2SO4 = H2 + FeSO4
  • Cu + H2SO4 = SO2 + 2H2O + SO42- + Cu2+


Sulfuric acid has different uses in various fields. Most of the H2SO4 (almost 60%) is used for fertilizers, 20% of this compound is consumed in the chemical industry like making detergents, synthetic resins, pharmaceuticals, petroleum catalysis, etc.

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