Chlorinated Lime (Calcium Hypochlorite, Ca(ClO)₂)
- S-1-Pharmaceutical Inorganic Chemistry
- Feb 26
- 2 min read
Updated: Mar 2
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Preparation
Chlorinated Lime Prepared by passing chlorine gas through slaked lime (calcium hydroxide):
2Ca(OH)2 + 2Cl2 → Ca(ClO)2 + CaCl2 + 2H2O2
Properties
White to grayish-white powder with a chlorine-like odor.
Soluble in water, forming a clear solution.
Strong oxidizing and bleaching agent.
Chemical formula: Ca(ClO)₂
Uses
As a disinfectant for water purification and swimming pools.
As an antiseptic for wound cleaning in dilute solutions.
Used for disinfecting surfaces in hospitals and households.
Storage of Chlorinated Lime
Store in a cool, dry place away from organic materials and reducing agents.
Keep in a tightly closed, corrosion-resistant container.
Assay of Chlorinated Lime (Calcium Hypochlorite)
Purpose
To determine the concentration or available chlorine content in chlorinated lime using iodometric titration.
Procedure
1) Prepare a Standard Solution
Dissolve a known amount of potassium iodide (KI) in water to create a standard solution.
2) Prepare the Sample
Weigh an accurate amount of chlorinated lime and dissolve it in a known volume of water.
3) React with KI
Add a known volume of KI solution to the chlorinated lime solution.
The available chlorine reacts with KI to produce iodine (I₂) and potassium chloride (KCl):
Cl2 + 2KI → I2 + 2KCl
4) Add Indicator
Add a starch solution as an indicator, which forms a blue-black complex with iodine.
5) Titrate
Slowly add a standard solution of sodium thiosulfate (Na₂S₂O₃) to the mixture while stirring.
Sodium thiosulfate reduces iodine to iodide:
2S2O32- + I2 → 2I- + S4O62-
The endpoint is reached when the blue-black color disappears, indicating all the iodine has reacted.
6) Calculate Available Chlorine Content
Measure the volume of sodium thiosulfate used in the titration.
Use the stoichiometry of the reactions to calculate the available chlorine content or purity of the chlorinated lime sample.
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