The exact density of cesium chloride (CsCl), which crystallizes in a Body-Centered Cubic (BCC) type structure, is 4.0 g/cm³.
Understanding Cesium Chloride's Crystal Structure
Cesium chloride forms a unique crystal structure often referred to as the "CsCl structure" or a "BCC type" lattice. While not a true Body-Centered Cubic lattice in the way elemental metals like iron are, its unit cell consists of a simple cubic arrangement of one ion type (e.g., Cl⁻) with the other ion type (Cs⁺) occupying the body-centered position. Alternatively, it can be viewed as a Cs⁺ ion at the corners of a simple cube and a Cl⁻ ion at its center.
- Coordination Number: In this arrangement, each cesium ion (Cs⁺) is surrounded by eight chloride ions (Cl⁻), and similarly, each chloride ion is surrounded by eight cesium ions. This gives both ions a coordination number of 8.
- Unit Cell Composition: Effectively, one formula unit of CsCl exists per unit cell, making it a relatively simple structure compared to face-centered cubic (FCC) derived structures like NaCl.
Key Properties of Cesium Chloride
The density of a crystalline solid depends on its molar mass, the volume of its unit cell, and Avogadro's number. For CsCl, these properties contribute to its measured density.
Here are some key properties of Cesium Chloride:
| Property | Value |
|---|---|
| Chemical Formula | CsCl |
| Molar Mass | ~168.36 g/mol |
| Crystal Structure | Body-Centered Cubic (BCC) type / CsCl structure |
| Lattice Parameter (a) | ~4.123 Å (at room temperature) |
| Melting Point | ~645 °C (1193 °F) |
| Solubility in Water | Soluble |
For more detailed information on crystal structures and their classifications, you can refer to resources on crystallography.
Practical Implications of CsCl Density
The high density of cesium chloride is leveraged in various scientific and industrial applications:
- Density Gradient Centrifugation: CsCl solutions are widely used to create density gradients for the separation of biomolecules such as DNA, RNA, and proteins. Due to its high solubility and density, CsCl can form stable gradients that allow for the isolation of macromolecules based on their buoyant density. This technique is fundamental in molecular biology research.
- Analytical Chemistry: Knowledge of CsCl's precise density is crucial for accurate measurements and calibrations in experiments involving its solutions.
- Material Science: Understanding the relationship between crystal structure and density helps in predicting and designing materials with desired physical properties.
The specific density of 4.0 g/cm³ for cesium chloride is a well-established value reflecting its atomic composition and the compact arrangement of ions within its BCC-type crystal lattice.
[[Inorganic Compound Density]]
