Calcium Hypochlorite

Calcium hypochlorite can be defined as a chemical compound having the formula Ca(ClO)2.

Commonly, it is referred to as either calcium oxychloride or bleaching powder. It can be said as an ionic compound, made up of two hypochlorite anions (ClO–) and a calcium cation (Ca2+). Despite being stable at room temperatures, calcium hypochlorite decomposes slowly in moist environments, giving it a characteristic 'chlorine' smell. The common name of calcium hypochlorite can be given as bleaching powder.

Calcium hypochlorite is a compound known to be an active ingredient in most commercial bleaching agents such as chlorinated lime and chlorine powder bleaching powder.

Calcium Hypochlorite Chemical Equation

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Commercially, calcium hypochlorite is available in its hydrated and anhydrous forms and is one of the primary ingredients of both bleaching powder and chlorine powder. The Ca(ClO)2 compound is produced on an industrial scale through the chlorine gas reaction with calcium hydroxide.

The chemical equation representation for this reaction can be given as follows.

2Ca(OH)2 + 2Cl2 → Ca(ClO)2 + H2O + CaCl2

In general, the bleaching powder is a calcium hypochlorite mixture, and its dibasic form can be given as (Ca(ClO2).2Ca(OH)2). In contrast, the dibasic form of calcium chloride can be given as (CaCl2.2Ca(OH)2). Because it contains two ClO– ions, this compound contains a high chlorine availability to that of sodium hypochlorite (NaOCl).

Structure of Calcium Hypochlorite

The Ca(ClO)2 molecule's structure consists of one Ca+ ion and two ClO– ions. The representation can be given as follows.

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Each chlorite ion holds a -1 charge, whereas the calcium ion holds a +2 charge. Thus, one calcium cation can form ionic bonds with the help of two hypochlorite ions.

Properties of Calcium Hypochlorite

Chemical Data

Physical Properties

• At room temperatures, the calcium hypochlorite compound is a white or grey solid.

• It has a water solubility of 21g/100 mL, and when dissolved, it reacts with the water.

• It has a hard water solubility of relatively low to that of its solubility in either soft or medium-hard water.

• Ca(ClO)2 compound has a strong chlorine smell (due to its reactions with water molecules present in air).

Chemical Properties

• Calcium hypochlorite compound acts as a strong base because it accepts H+ readily. Also, when dissolved in water, the hypochlorite anion accepts a proton from H2O by liberating OH– ion.

• The chemical equation for this reaction can be given by ClO- + H2O → HClO + OH-

• This is also a compound, which is a powerful oxidizing agent because it can accept an electron readily.

• Calcium hypochlorite is a compound that reacts with hydrochloric acid by yielding water, calcium chloride (CaCl2), and also chlorine gas (Cl2).

• The chemical equation for this reaction can be given as 4HCl + Ca(ClO)2 → CaCl2 + Cl2 + H2O.

Production of Calcium Hypochlorite

Calcium hypochlorite is a compound that is industrially produced by treating lime (Ca(OH)2) with chlorine gas. This reaction is conducted in stages to produce various compositions, each with a different calcium hypochlorite concentration, together with the unconverted calcium chloride and lime. The chemical representation can be shown as,

2 Cl2 + 2 Ca(OH)2 → Ca(CIO)2 + CaCl2 + 2 H2O

Bleaching powder is prepared with a moist slaked lime slightly. It is also not a simple mixture of calcium chloride, calcium hydroxide, and calcium hypochlorite. However, instead, it is a mixture that principally contains the dibasic calcium hypochlorite, calcium hypochlorite Ca(ClO)2, Ca3(ClO)2(OH)4 (can also be written as Ca(ClO)2 · 2 Ca(OH)2), and the dibasic calcium chloride, Ca3Cl2(OH)4 (calcium hydroxy chloride, which is also written as CaCl2 · 2 Ca(OH)2).

Calcium Hypochlorite Uses

The Ca(ClO)2 compound is often used to disinfect large volumes of water by making it safe to drink. It can also be used widely in swimming pools to sanitize water bodies and destroy the germs present in it. A few other primary calcium hypochlorite uses are listed below.

• Because it is a good oxidizing agent, this is quite useful in the field of organic chemistry.

• It can be used to obtain fragmented aldehydes or carboxylic acids by cleaving the glycols and keto acid bonds.

• The Ca(ClO)2 compound is used in the haloform reaction, yielding chloroform.

• It can be used to disinfect both drinking water and wastewater because it has a high chlorine availability.

• Calcium hypochlorite is used in some bleaching solutions as well.