1. Physical Properties
- Appearance: Calcium bromide typically appears as a white, crystalline solid (powder or granules) at room temperature. It is also commonly found and used as a clear, colorless to slightly yellow aqueous solution.
- Odor: It is odorless.
- Density:
- Solid: The anhydrous salt has a high density of approximately 3.35 g/cm³.
- Solution: The density of its aqueous solution is highly concentration-dependent. Solutions used in oilfield applications range from about 1.2 to 1.7 g/cm³ (10-16 lbs/gal) or even higher.
- Solubility: It is highly soluble in water. Its solubility is also excellent in other solvents like ethanol, acetone, and methanol.
- Hygroscopicity: It is deliquescent, meaning it readily absorbs moisture from the air and can dissolve in its own absorbed water.
- Melting Point: It has a relatively high melting point of 730°C (1,346°F).
- pH: Aqueous solutions of calcium bromide are neutral or slightly basic (pH ~7-8) due to the hydrolysis of the bromide ion.
2. Chemical Properties
- Chemical Formula: CaBr₂ (often found as the dihydrate, CaBr₂·2H₂O)
- Molecular Weight: 199.89 g/mol (anhydrous)
- Reactivity: It is a relatively stable compound.
- Deliquescence: As a deliquescent solid, it must be stored in sealed containers to prevent absorption of atmospheric moisture.
- Reactions: It can participate in typical halide reactions. For example, it reacts with silver nitrate (AgNO₃) to form a pale yellow precipitate of silver bromide (AgBr), a common test for bromide ions.
CaBr₂ + 2AgNO₃ → 2AgBr↓ + Ca(NO₃)₂
- Toxicity: While not severely toxic, it can be irritating to the skin, eyes, and respiratory system. Prolonged exposure should be avoided.
Summary of Key Characteristics
| Property | Description |
|---|---|
| Appearance | White crystalline solid or clear colorless solution |
| Solubility | Very high in water, alcohol, and acetone |
| Density (Solid) | ~3.35 g/cm³ |
| Density (Solution) | 1.2 – 1.7+ g/cm³ |
| Hygroscopicity | Deliquescent (absorbs moisture from air) |
| Melting Point | 730 °C (1,346 °F) |
| pH in Water | Neutral to slightly basic |
