Hocl lewis structure,Characteristics:27 Facts You Should Know


HOCl lewis structure and all its related facts are going to be discussed here.

HOCl or hypochlorous acid is a disinfectant which is formed by the reaction between chorine and water. It gets itself dissociated into ClO in water. Both HClO and ClO are good oxidizers.

HClO is a colourless liquid with molar mass 52.46g/mol. It is non- flammable and non- toxic characteristics. White blood cells of mammals produce hypochlorous acid for fight against foreign bodies. In low concentrations it can be applied on open wounds to get disinfectant action.

Uses of hypochlorous acid are as follows

  • In organic synthesis it can be used for the conversion of alkene to chlorohydrins.
  • Being a good disinfectant it can be used in offices, hospital, clinics.It can be used as a sanitizer.
  • Foul smell from garbage, rotten meat, and toilet can be removed by using hypochlorous acid.

Let’s go through some important facts about HOCl

Lewis Structure of HOCl


The Lewis structure is actually a representation of bonds and lone pairs involved between atoms when they combines to form a stable compound. Lewis structure of any molecule can be drawn by understanding some basic rules and concepts.

  • First, ascertain how many valence electrons are involved in total. We know that oxygen has 6, hydrogen has 1 and chlorine has 7 valence electrons. So in total there is 14 electrons involved here in bond making.
  • Second step is to assign the bonds in between the atoms. Oxygen is the central atom with hydrogen and chlorine on either sides.
  • Make two bonds between them using four electrons and then distribute remaining electrons around oxygen and chlorine by fulfilling its octet.
  • After the calculation of formal charge of the compound then it is zero . So this will be the most stable Lewis structure of hypochlorous acid.
hocl lewis structure
Lewis Structure of HOCl

Resonance in HOCl

Resonance is the delocalisation of electrons involved in a bond. Resonance tends to form more than one structure to a compound. Presence of double bond, lone pairs results resonance into action. While making the resonance the structure of the molecule didn’t change. Since there is no double bond resonance can’t be observed in hypochlorous acid.

Shape and Bond Angle of HOCl


The shape of the molecule is mainly determined by the orientation of electron pairs around the atom. Hypochlorous acid has a bent shape due to lone pair lone pair repulsion. There is one O-H and O-Cl bond with bond length 97 pm and 169.3 pm respectively. The bond angle is found to be 103.30.

Shape and Angle of HOCl

Formal charge of HOCl

Formal charge of an atom is a charge assigned to an atom when it makes a bond. The formula for finding formal charge is
Formal charge = Valence electrons – No. of non bonded electrons – No. of bonds


Formal charge of chlorine = 7-6-1 = 0
Formal charge of oxygen = 6-4-2 = 0
Formal charge of hydrogen = 1-0-1 = 0

 So the formal charge of HOCl is zero.

Octet rule

According to octet rule every atom should have eight electrons in its valence shell after bond making. Atoms obeying this rule will have a stable existence. Here in hypochlorous acid oxygen with six electrons get two more after bond making to make its octet filled.

Similarly chlorine with seven electrons gets one more after bond making. Hydrogen also gets two electrons to get resemble with helium to get stable existence. So here all the atoms are stable and obeys octet rule.


Lone Pairs in HOCl

Lone pairs or non- bonded electrons are the electrons which don’t involve for bond formation. Lone pairs in oxygen and chlorine is 2 and 3 respectively. So there in total 10 non bonded electrons in hypochlorous acid.

Valence Electrons in HOCl

The total electrons involved in bond making are its valence electrons. The total electrons involved in the formation of hypochlorous acid are 14.

Hybridisation in HOCl

Hybridisation is the overlapping atomic orbitals with different energy to form orbitals with same energy. Such orbitals are called hybrid orbitals. The hybridisation of a compound can be found through the below equation.

Hybridisation = ½ ( V+M-C+A)

V = No of valence electrons present, M = monovalent atoms, C = positive charge, A = negative charge

Oxygen is the central atom in HOCl. So its hybridisation is

Hybridisation = ½ ( 6+2-0+0) = 8/2 = 4

Oxygen atom being the central atom HOCl follows sp3 hybridization. So it meant to have tetrahedral geometry with bond angle 1090. However, the electrons in oxygen atoms repel one another, preventing the oxygen atoms from taking on a tetrahedral structure. So the shape is changed to bent with bond angle 1030.

Solubility of HOCl

Hypochlorous acid is soluble in water.

Is HOCl is Weak Acid ?

Hypochlorous acid is found to be a weak acid. The ease with which a substance donates protons when dissolved in water is known as its acidity. Acid strength is indicated by the acid dissociation constant, or pka value. If the pka value of an acid is less than zero then it’s a strong acid and if it’s is greater than zero then it’s  weak acid. The pka value of hypochlorous is 7.53. So it is a weak acid.

Is HOCl Linear ?

HOCl is not a linear shaped molecule it is bent shape molecule due to repulsion.

Is HOCl an Electrophile ?

HOCl can acts as electrophile. An electrophile is an electron loving atom with positive charge which usually get attached to electron rich centre. The chlorine atom in hypochlorous acid is an electrophile which usually gets attached with alkene to form chlorohydrins.

Is HOCl is Polar ?

HOCl is a polar molecule. Polarity of a compound can be found through the electronegativity difference of atoms involved and the orientation of bonds. In HOCl the electro negativities of oxygen, chlorine, hydrogen is 3.4, 3.16,2.2 .

Here the repulsion of electrons between the atoms makes its shape changed to bent. So due to change in electronegativity and asymmetric structure hypochlorous acid is a polar molecule.

Is HOCl is Stronger than HOBr ?

HOCl is more stronger than HOBr. On comparing the pka values of both HOCl and HOBr hypochlorous acid has lower pka value with strong acidic character. Also the when comparing the electronegativity of halogen chlorine is most electronegative than bromine. So hypochlorous acid is more stronger than hypobromous acid.

Is HOCl a Oxidising Agent ?

Hypochlorous acid is found to be strong oxidising agent. An oxidising agent is a substance which gets reduced while oxidising another substances. So a good oxidising agent has lower oxidation number.  The oxidation number of chlorine is +1 . Therefore HOCl acts as good oxidizer.

Is HOCl a Bleaching Agent ?

HOCl is a good antimicrobial agent it is not a bleaching agent. Sodium hypochlorite, NaOCl can be considered as a good bleaching agent.

Is HOCl and NaOCl a buffer ?

A buffer is a solution which resists changes in pH when acid or base is added into it. HOCl and NaOCl is good buffer solution with pH range 7.32.

Does HOCl makes Hydrogen Bond ?

HOCl makes hydrogen bonds with each other. Hydrogen bond is the bond formation between hydrogen and an electronegative atom like oxygen, chlorine, Fluorine etc. There are two types of hydrogen bond. Intermolecular and Intramolecular hydrogen bonds.

In intermolecular hydrogen bonding hydrogen gets attached with electronegative atom of another molecule. In intramolecular hydrogen bonding hydrogen atom of one molecule gets attached with electronegative atom of same molecule.

Here HOCl makes intermolecular hydrogen bonds with hydrogen atom of one HOCl molecule with electronegative atom of another HOCl molecule.

Is HOCl Corrosive ?

HOCl can be corrosive or irritant to skin or metals depending upon its concentrations and pH levels.

Is HOCl is Ionic or Covalent ?

HOCl is covalent compound. The two bonds formed here is one O-H bond and one O-Cl bond. It is made through the mutual sharing of electrons between the atoms.

Is HOCl a Gas ?

HOCl is a colourless liquid.

Is HOCl is Stable ?

HOCl is stable substance under normal conditions.

Is HCl is Stronger than HOCl ?

HCl is stronger than HOCl. The pka values of HCl is -5.9 that indicates it’s a strong acid. While the pka value of HOCl is 7.53 . We know that acids with high pka values will be weak acids. So HOCl is weaker acid and HCl is a strong acid.

Is HOCl Stronger than HOI ?

HOCl is stronger than HOI. Hypochlorous acid has a pka value of 7.53 while hypoiodous acid has 10.5. Higher the pka value then that will be weak in acidic character. So HOCl with lower pka value will be more stronger than hypoiodous acid.

Is HOCl is Tetrahedral ?

HOCl follows sp3 hybridization supposed to tetrahedral geometry. But due to some repulsion factors in order to get stable existence the atoms itself arrange them to a bent structure instead of tetrahedral shape.

Is HOCl Stronger than Bleach ?

HOCl is good disinfectant which is 80-200 times more effective than bleach for surface disinfection. It is charge less with relatively low molar mass enables to penetrate into cell walls than any other chlorine based disinfectant.

Conclusion

Hypochlorous acid or HOCl is a weak acid with polar character. Its Lewis structure and all other details like its Hybridisation, solubility etc were discussed with all details in this article.

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