What is Calcium Hypochlorite Definition Formula Preparation Reactions and Uses
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.
FAQs on Calcium Hypochlorite Structure Properties and Applications
1. What is calcium hypochlorite?
Calcium hypochlorite is an inorganic compound with the chemical formula Ca(ClO)2 used mainly as a disinfectant and bleaching agent. It contains calcium ions (Ca2+) and hypochlorite ions (ClO-).
- Commonly known as bleaching powder or pool chlorine.
- Appears as a white or grayish solid with a strong chlorine smell.
- Releases chlorine when dissolved in water, which gives it strong oxidizing and antimicrobial properties.
2. What is the chemical formula for calcium hypochlorite?
The chemical formula for calcium hypochlorite is Ca(ClO)2. It consists of:
- One Ca2+ ion
- Two ClO- (hypochlorite) ions
3. How is calcium hypochlorite prepared?
Calcium hypochlorite is prepared by passing chlorine gas over dry calcium hydroxide. The simplified balanced reaction is:
2Ca(OH)2(s) + 2Cl2(g) → Ca(ClO)2(s) + CaCl2(s) + 2H2O(l).
- Chlorine acts as an oxidizing agent.
- The product is a mixture commonly called bleaching powder.
- The solid is then processed and dried for commercial use.
4. What happens when calcium hypochlorite is added to water?
When calcium hypochlorite is added to water, it forms hypochlorous acid (HOCl), which acts as a powerful disinfectant. The key reaction is:
ClO-(aq) + H2O(l) ⇌ HOCl(aq) + OH-(aq).
- HOCl kills bacteria, viruses, and algae.
- The solution becomes slightly basic due to formation of OH-.
- This reaction explains its use in swimming pool chlorination and water treatment.
5. Why is calcium hypochlorite used for water purification?
Calcium hypochlorite is used for water purification because it releases hypochlorous acid (HOCl), a strong oxidizing agent that kills microorganisms. Its advantages include:
- Effective destruction of bacteria, viruses, and protozoa.
- Easy storage and transport in solid form.
- Long shelf life compared to liquid chlorine.
6. What type of compound is calcium hypochlorite?
Calcium hypochlorite is an ionic compound and a strong oxidizing agent. It is composed of:
- Metal cation: Ca2+
- Polyatomic anion: ClO-
7. How do you calculate the molar mass of calcium hypochlorite?
The molar mass of calcium hypochlorite (Ca(ClO)2) is approximately 142.98 g/mol. Calculation steps:
- Ca = 40.08 g/mol
- Cl = 35.45 × 2 = 70.90 g/mol
- O = 16.00 × 2 = 32.00 g/mol
8. What is the difference between calcium hypochlorite and sodium hypochlorite?
The main difference between calcium hypochlorite and sodium hypochlorite is that Ca(ClO)2 is a solid calcium salt, while NaClO is a liquid sodium salt solution. Key differences:
- Calcium hypochlorite (Ca(ClO)2): solid, higher available chlorine content.
- Sodium hypochlorite (NaClO): liquid bleach, less stable over time.
- Calcium hypochlorite is preferred for pools; sodium hypochlorite is common household bleach.
9. Is calcium hypochlorite acidic or basic?
Calcium hypochlorite is basic in aqueous solution because it produces hydroxide ions (OH-). The equilibrium reaction is:
ClO-(aq) + H2O(l) ⇌ HOCl(aq) + OH-(aq).
- Formation of OH- increases pH.
- Solutions are typically alkaline.
- This basic nature affects pool water pH control.
10. What are the safety hazards of calcium hypochlorite?
Calcium hypochlorite is a strong oxidizer and can be hazardous if mishandled. Major safety concerns include:
- Reacts with acids to release toxic chlorine gas:
Ca(ClO)2(s) + 4HCl(aq) → CaCl2(aq) + 2Cl2(g) + 2H2O(l) - May cause fire when in contact with organic materials.
- Can irritate skin, eyes, and respiratory tract.
