No, bleaching powder does not dissolve completely in water. Instead, it forms a suspension, meaning some parts remain undissolved.
Understanding Bleaching Powder's Solubility
Bleaching powder, chemically known as Calcium Hypochlorite (though commercially it's a mixture), is not a single, simple compound. Its complex nature is the primary reason it doesn't fully dissolve when added to water.
Why It Doesn't Dissolve Completely
According to the provided reference, bleaching powder is a "quite complex molecule." It contains various other heavy calcium salts in addition to its primary active component. These additional salts contribute to its incomplete solubility.
Specifically, the components that remain largely insoluble in water include:
- Calcium Chloride (CaCl₂): While calcium chloride itself is typically very soluble, in the context of bleaching powder, it's often present in forms or complexes that don't fully dissolve.
- Calcium Hydroxide (Ca(OH)₂): Also known as slaked lime, calcium hydroxide has very low solubility in water.
- Calcium Hypochlorite (Ca(OCl)₂): This is the active ingredient responsible for bleaching, and while it does react with water to release hypochlorous acid, the bulk compound itself does not completely dissolve into a true solution.
These "heavy calcium salts" are the primary culprits for the undissolved residue you observe when mixing bleaching powder with water.
To illustrate the solubility of its key constituents:
| Component | Typical Solubility in Water | Contribution to Undissolved Residue |
|---|---|---|
| Calcium Hydroxide | Low | Significant |
| Calcium Hypochlorite | Partial/Reacts | Some |
| Other Calcium Salts | Varies (often low) | Can be significant |
In summary, when bleaching powder is added to water, it primarily forms a milky suspension rather than a clear solution, due to the presence of these various insoluble calcium compounds.
