Chemical Composition and Differences

Chloride of lime, also known as bleaching powder, is a compound with the chemical formula Ca(ClO)2. On the other hand, calcium chloride is a compound with the formula CaCl2.

Composition of Chloride of Lime
1. Chloride of lime is made up of calcium hypochlorite, which is a combination of calcium cations (Ca2+) and hypochlorite anions (ClO-).
2. The hypochlorite anions in chloride of lime provide it with its bleaching and disinfectant properties.

Composition of Calcium Chloride
1. Calcium chloride is composed of calcium cations (Ca2+) and chloride anions (Cl-).
2. It is a hygroscopic compound, meaning it readily absorbs moisture from the air.

Difference in Chemical Structures
The main chemical difference between chloride of lime and calcium chloride lies in the presence or absence of the hypochlorite anion. While chloride of lime contains calcium hypochlorite, calcium chloride does not have any hypochlorite component.

Gradual Loss of Chlorine
When chloride of lime is exposed to air, it gradually loses its chlorine content due to a process called decomposition. This decomposition occurs through a series of chemical reactions.

Reaction Mechanism
1. In the presence of moisture, the hypochlorite anions in chloride of lime react with carbon dioxide (CO2) in the air to form calcium carbonate (CaCO3) and chlorine gas (Cl2).
2. The reaction can be represented as follows:
Ca(ClO)2 + CO2 → CaCO3 + Cl2

Factors Affecting Decomposition
The rate of chlorine loss from chloride of lime depends on several factors:
1. Moisture: The presence of moisture is essential for the reaction to occur. Dry chloride of lime does not decompose as readily.
2. Temperature: Higher temperatures can accelerate the decomposition process.
3. Exposure to Light: Light, especially sunlight, can also promote the decomposition of chloride of lime.

Summary
Chloride of lime and calcium chloride differ in their chemical compositions, with chloride of lime containing calcium hypochlorite and calcium chloride consisting of calcium cations and chloride anions. When chloride of lime is exposed to air, it gradually loses chlorine due to decomposition. This decomposition occurs through a reaction with carbon dioxide in the air, resulting in the formation of calcium carbonate and chlorine gas. Factors such as moisture, temperature, and exposure to light influence the rate of decomposition.

Ca(OH)2+Cl2->CaOCl2+H2O