Sodium Hypochlorite

What is Sodium Hypochlorite?

Sodium hypochlorite is an ionic chemical compound with the formula NaOCl. It comprises sodium cation and hypochlorite anion. It is known by various other names such as antiformin, bleach etc. It is generally found in its pentahydrate state. As its anhydrous form is unstable and decomposes explosively. Sodium hypochlorite pentahydrate is a pale greenish – yellow solid which is stable and not explosive. It is widely used as a cleaning agent or as a bleach. 

Formula of Sodium Hypochlorite 

S. No.

IUPAC Name & Formula of Sodium Hypochlorite 

1.

Empirical Formula 

NaOCl

2.

Molecular Formula 

NaOCl or NaClO 

3.

Skeletal formula

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4. 

IUPAC name 

Sodium hypochlorite 

5. 

Other general names 

Antiformin, bleach, chloride of soda 


Structure of Sodium Hypochlorite 

Sodium hypochlorite is a salt made up of sodium cation and hypochlorite anion. It is also known as the sodium salt of hypochlorous acid (HOCl). Its structure is given below –

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Properties of Sodium Hypochlorite 

Sodium hypochlorite shows following physical and chemical properties –

  • Its molar mass is 74.4 g.mol-1.

  • Sodium hypochlorite pentahydrate is a greenish yellow solid. 

  • It has chlorine like and a sweetish odor. 

  • Its melting point is 18 .

  • Its boiling point is 101 .

  • It is soluble in water. 

  • Its density is 1.11 g.cm-3.

  • It is corrosive.

  • Sodium hypochlorite is unstable and explosive although sodium hypochlorite pentahydrate is stable at lower temperatures and non-explosive. 

  • It decomposes at high temperature and forms sodium chlorate and sodium chloride. Reaction is given below –

3NaOCl (aq) → 2NaCl(aq) + NaClO3(aq)

  • It is used in oxidation of starch. 

  • Oxidation of metals – Sodium hypochlorite reacts with metals and forms metal oxide by oxidizing them. Reaction is given below –

NaOCl + Mg 🡪 MgO + NaCl

  • Reaction with ammonia - Sodium hypochlorite reacts with NH3 and forms sodium hydroxide and NH2Cl. Reaction is given below –

NH3 + NaOCl → NH2Cl + NaOH

  • Reaction with monochloramine – Sodium hypochlorite reacts with monochloramine and forms sodium hydroxide and dichloramine. Reaction is given below –

NH2Cl + NaOCl → NHCl2 + NaOH

  • Reaction with dichloramine – Sodium hypochlorite reacts with dichloramine and forms sodium hydroxide and nitrogen trichloride. Reaction is given below –

NH2Cl + NaOCl → NCl3 + NaOH


Production of Sodium Hypochlorite 

Sodium hypochlorite can be prepared by various methods. Few of them, we are discussing here. 

  • By chlorination – Aqueous sodium hydroxide reacts with chlorine and gives sodium chloride, sodium hypochlorite and water. This was given by French chemist Antoine Labarraque. The reaction is given below –

Cl2 + 2NaOH 🡪 NaCl + NaOCl + H2O

In the above reaction, chlorine is getting oxidized and reduced simultaneously. So, the reaction is disproportionation. 

  • By calcium hypochlorite – When washing soda (sodium carbonate) reacts with bleaching powder (calcium hypochlorite) then sodium hypochlorite and calcium carbonate are formed. Reaction is given below –

Na2CO3 + Ca(OCl)2 🡪 CaCO3 + NaOCl 

  • By ozone and sodium salt – Sodium chloride reacts with ozone and forms sodium hypochlorite and oxygen. Reaction is given below –

NaCl + O3 🡪 NaOCl + O2

  • By electrolysis – Sodium hypochlorite can be prepared by electrolysis of brine. Brine is a highly concentrated solution of sodium chloride in water. This method was discovered by Chemist E.S. Smith. It is known as chloralkali process. 


Uses of Sodium Hypochlorite 

Sodium hypochlorite is a very useful compound. It is used in many fields for various purposes. Few of its applications are listed below –

  • It is used as bleach. Household bleach solutions generally contain 3-8% of sodium hypochlorite by weight. 

  • It is used for cleaning purposes such as to remove mold stains, dental stains etc. 

  • It is used as a disinfectant. It has anti – microbial ability which makes it very useful in hospitals as disinfectant. It is used in Dakin’s solution as well. 

  • It has deodorizing and caustic effects which makes it even more useful for cleaning and laundry. 

  • It is used in treatment of wastewater. 

  • Due to its effectiveness against pathogenic organisms, it is used in endodontic therapy. 

  • Soaps containing sodium hypochlorite are being used for treatment of eczema in humans for decades. 


Sodium Hypochlorite: Summary in Tabular Form 

Sodium Hypochlorite 

Chemical formula 

NaOCl 

IUPAC Name 

Sodium hypochlorite 

Other names 

Antiformin, bleach, chloride of soda 

Molar mass 

74.4 g/mol

Melting point 

18

Boiling point 

101

Density 

1.11 g.cm-3

Appearance 

Greenish yellow solid 

Odor 

Chlorine like smell 

State at STP

Liquid (solid for pentahydrate)

Solubility in water 

It is soluble in water (29.3 g/100ml)

Preparation 

By chlorination – 

Cl2 + 2NaOH 🡪 NaCl + NaOCl + H2O

By calcium hypochlorite – 

Na2CO3 + Ca(OCl)2 🡪 CaCO3 + NaOCl

By electrolysis of brine (concentrated solution of NaCl and water)

By ozone and sodium salt –

NaCl + O3 🡪 NaOCl + O2

Main properties 

Its bleaching and deodorizing properties. 

Main use 

As a disinfectant and cleansing agent. 

Disadvantage 

Corrosive 

Difficulty in storage


This ends our coverage on the topic “Sodium hypochlorite”. We hope you enjoyed learning and were able to grasp the concepts. We hope after reading this article you will be able to solve problems based on the topic. If you are looking for solutions of NCERT Textbook problems based on this topic, then log on to Vedantu website or download Vedantu Learning App. By doing so, you will be able to access free PDFs of NCERT Solutions as well as Revision notes, Mock Tests and much more.