7 Easy Steps on HClO Lewis Structure, Hybridization (Solved)

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Hypochlorous acid (HClO) has a Lewis structure with a chlorine (Cl) atom at the center, bonded to an oxygen (O) atom and a hydrogen (H) atom. Cl has 7 valence electrons, O has 6, and H has 1, totaling 14 electrons. The structure shows a single Cl-O bond, a single O-H bond, and three lone pairs on Cl. The molecule adopts a bent geometry with an O-Cl-H bond angle slightly less than 120°, due to lone pair-bond pair repulsion. The electronegativity difference between Cl (3.16) and O (3.44) creates a polar bond, influencing HClO’s reactivity, particularly in oxidation and disinfection processes.

HClO or hypochlorous acid is discovered by a French chemist, Antoine Jerome in 1834. HOCl is a weak acid with a molar mass 52.46 g/mol. It is a bent shaped molecule having two lone pair of electrons on central atom (oxygen) and it is dissolved in water to give chlorine because it is an oxyacid of chlorine.

Let’s focus on the following topics of discussion on HClO.

How to draw HClO lewis structure?

Lewis structure is defined as the structural representation of any molecule in which the lone pairs will be shown around the participating atoms as the electron dots.

  1. Determining the number of valance electrons: Valance electrons have a great role in determining the lewis structure. H, Cl and O has 1, 7 and 6 electrons in their respective outer most shell.
  2. Finding out the bonding electrons: In HClO, total two sigma (single) bonds are present. Thus 2×2 =4 electrons are involved in covalent bond formation.
  3. Finding out the nonbonding electrons: In hypochlorous acid, chlorine and oxygen have total three and two pairs of nonbonding electrons respectively which are shown around them.
hclo lewis structure
HClO Lewis Structure

HClO Lewis Structure Shape

Molecular shape is determined by considering the following factors-

  • Hybridization of central atom
  • Any lone pair bond pair repulsion present or not.

In HClO, the central atom, oxygen is sp3hybridized and any according to the theory, any sp3hybridized atom will be tetrahedral shaped if no type of bond pair lone pair repulsion is present.

But in HClO, four nonbonding electrons are present in oxygen atom. These lone pairs are involved in these repulsions-

  1. Lone pair-lone pair repulsion
  2. Lone pair-bond pair repulsion

Besides these, another repulsion is also present, bond pair-bond pair repulsion. As lone pair-lone pair repulsion is more powerful than lone pair-bond pair repulsion, the shape of HClO will be bent in shape (decreasing the bond angle than the ideal)

HOCl shape
Shape of HOCl

HClO Lewis Structure Formal Charge

Formal charge is calculated to find out the most stable lewis structure. Lewis structure having maximum number of formal charge is zero will be the most stable configuration.

  • Formal charge = Total number of valance electrons – number of electrons remain as nonbonded – (number of electrons involved in bond formation/2)
  • Formal charge of hydrogen = 1 –0 – (2/2) = 0
  • Formal charge of oxygen = 6 – 4 – (4/2) = 0
  • Formal charge of chlorine = 7 – 6 – (2/2) = 0

Hydrogen and chlorine are involved in single bond with oxygen atom individually whereas oxygen is involved in two bond formation. Thus, the bonding electrons for oxygen is 4 and for hydrogen and chlorine is 1.

 HClO Lewis Structure Angle

Angle basically indicates the bond angle which depends on the hybridization of central atom as well as the repulsion involving bond pairs and lone pairs present in the molecule.

In HClO, both the oxygen and chlorine atom have lone pairs. Oxygen has two lone pairs involving in lone pair-lone pair repulsion which decreases the angle between the O-Cl and O-H bonds.

Central atom, oxygen is sp3 hybridized. Thus, the ideal structure will be tetrahedral and ideal bond angle should be 109.50. Due to the presence of the repulsion the ideal bond angle (109.50) is deviated and the actual angle becomes 1030 because the lone pair-lone pair repulsion closes the bond angle and bond pair-bond pair repulsion opens up the bond angle.

Lone pair-lone pair repulsion is greater repulsive factor than the lone pair-bond pair repulsion. So, lone pair-lone pair repulsion closes the bond angle more than the opening up of the bond angle by bond pair-bond pair repulsion.

HClO Lewis Structure Octet Rule

Octet rule is one of the most important rules which states than any atom in a molecule should contain such electron configuration which matches with their nearest noble gas valence shell electron configuration. In HClO all the constituent atoms, hydrogen, oxygen and chlorine obey octet rule.

Hydrogen has only one valence shell electron. After bonding with oxygen it has two electrons shared with oxygen and matches with the nearest noble gas, helium’s electron configuration. Oxygen has six valence electrons and after formation of two bonds with hydrogen and chlorine, it fulfils its octet having the eight electrons. Chlorine has seven outer most shell electrons and it also fulfils its octet after bonding with oxygen.

Thus, octet rule is fully satisfied in HClO molecule.

HClO Lewis Structure Lone Pairs

Lone pairs and nonbonding electron pairs are similar term. They indicate those outer most shell electrons which are not involved in bond formation with the other atoms. One of the most significant roles of lone pairs is to determine the shape of any molecule.

  • Nonbonded electron = Total number of valance electron – number of bonded electrons.
  • Nonbonding electrons of hydrogen = 1 – 1 = 0
  • Nonbonding electrons of oxygen = 6 – 2 = 4
  • Nonbonding electrons of chlorine = 7 – 1 = 6

Thus, total nonbonding electrons in HClO are = 0+4+6 = 10

HClO Valence Electrons

Valence electrons are basically the outer most shell electrons of any atom which are the most loosely bound to the nucleus and most reactive with comparing to the inner shell electrons.

Hydrogen has only one electron in its first 1s orbital which is its valence shell electron. Oxygen has atomic number eight (1s2 2s2 2p4). Within these eight electrons six electrons are regarded as the valence shell electrons.

Chlorine has total 17 electrons among these 17, seven electrons are the valence shell electrons (3s2 3p5).

HClO Solubility

Hypochlorous acid or HClO is a weak acid with the acid dissociation constant (ka) is 3.0×10-8. Thus, it is soluble in water. HClO is generated when chlorine dissolves in water. After formation it quickly dissociates into hypochlorite.

Is HClO an electrolyte?

Electrolytes are those who can dissociated into its constituent ions after dissolving in water. Electrolytes are basically two types-

  1. Strong electrolyte
  2. Weak electrolyte

Strong electrolytes are dissociated almost 100% in water but the percentage of dissociation is very less for an weak electrolyte.

HClO is a weak acid. When it is dissolved in water the percentage of dissociation is very less. Maximum molecules of HClO remain as undissociated state. Thus, HClO is a weak electrolyte.

Is HClO acidic or basic?

Hypochlorous acid or HClO is a weak acid. It donates proton in aqueous solution. It is formed after the dissolution of chlorine in water. Due to partial dissociation, HClO generates ClO– and H+ in water.

HClO is a lewis monoprotic acid. Lewis acids donate H+ ions in water. It is monoprotic acid because from a single HClO molecule, only one H+ ion is obtained. Polyprotic acids are those which give more than one H+ ion like H2SO4.

 Is HClO polar or nonpolar?

Polarity of any molecule depends upon the following parameters-

  • Electronegativity difference between the atoms
  • Orientation of the bonds present in the molecule

HClO is a bent shaped molecule having the bond angle 1030. There is also a difference in electronegativity between H, Cl and oxygen (electronegativity of hydrogen, oxygen and chlorine are 2.2, 3.4 and 3.16 respectively in Pauling scale). Besides that, the lone pairs generate an uneven distribution of charges.

Thus, it is definitely a polar molecule.

Is HClO ionic or covalent?

HClO is a covalent molecule. Oxygen is attached with hydrogen and chlorine atom by two covalent bonds. In this compound the valence electrons of each of the atoms are not completely transferred from one atom to another atom. They are sharing their valence electrons with each other to fill their respective octet.

Ionic compounds are those which are permanently transferring their valence shell electrons not sharing with each other. This is not happened in HClO. The electronegativity difference between the atoms is also not high. But in any ionic compound, one must be electropositive compound like any metal and another should be electronegative metal. In HClO, there is no metal and nonmetal combination is present.

Is HClO hydrogen bonding?

Hydrogen bonds are formed between hydrogen atom (attached with any electronegative atom) with any  highly electronegative atom like oxygen, nitrogen. Hydrogen bonding can be two types-

  1. Intermolecular hydrogen bonding
  2. Intramolecular hydrogen bonding

In HClO, oxygen and chlorine both are electronegative. But oxygen is more electronegative than chlorine. Thus it can participates intermolecular hydrogen bonding with the hydrogen of any other HClO atom.

But intramolecular hydrogen bonding is not possible in HClO.

Is HClO stronger than HBrO?

Yes, HClO is stronger acid than HBrO.

The main reason of the greater acidity of HClO is due to the higher electronegativity of chlorine with comparing to bromine. Thus, the polarity of O-H bond becomes greater in HClO than HBrO. Because chlorine attracts the bonded electrons of O-Cl bond in greater extent. So, the elimination of H+ ion will be easier in HClO with respect to HBrO.

For the same reason HClO is stronger acid than HIO and weaker acid than HFO because iodine is less electronegative and fluorine is more electronegative than chlorine.

 Is HClO stronger than HClO4?

No, HClO4 is stronger acid than HClO.

Stability of the conjugate base is the main reason of the greater stability of HClO4. H+ can be easily removed from HClO4 to form ClO4– because of its extra stability. This extra stability of clo4- is due to the conjugation present in the conjugate base. But the conjugate base ClO– has no such extra stabilization.

HClO4 ⇌ H+ + ClO4–

HClO ⇌ H+ + Cl–

This equilibrium is shifted towards right more in HClo4 than HClO. Thus, the elimination of H+ will be facile in HClO4 than HClO.

From this article, it is concluded about HClO that it is a bent shaped molecule with the central atom hybridization sp2. It is a weak acid as well as a weak electrolyte.

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