Physical Properties of Calcium Carbide

Calcium carbide (CaC₂) is a solid inorganic compound with distinct physical characteristics that influence its handling, storage, and industrial applications. Below is a detailed breakdown of its key physical properties, including color, odor, density, and thermal behavior.

1. Color​

Calcium carbide typically appears as grayish-black to dark brown crystalline solids​ or irregular lumps. The color arises from trace impurities (e.g., carbon, calcium oxide) and variations in crystal structure. High-purity grades (≥95% CaC₂) tend to be darker, while lower-purity industrial grades may show lighter gray hues.

2. Odor​

Fresh calcium carbide has a mild, earthy odor, but it is often associated with a sharp, garlic-like smell​ due to:

Trace Impurities: Contaminants like phosphorus or sulfur compounds (common in low-grade CaC₂) release volatile gases (e.g., phosphine, hydrogen sulfide) during hydrolysis.

Reaction Byproducts: When exposed to moisture, calcium carbide reacts to produce acetylene gas (C₂H₂), which has a faint garlic-like aroma.

3. Density​

The density of calcium carbide depends on its form (lumps, granules, or powder) and purity:

Bulk Density: ~2.22 g/cm³ (for solid lumps or granules).

True Density: ~2.34 g/cm³ (measured for pure crystalline CaC₂).

Powder Density: Finely ground powder has a lower bulk density (~1.5–1.8 g/cm³) due to increased air gaps between particles.

4. Melting Point​

Calcium carbide does not melt​ under standard atmospheric pressure. Instead, it sublimes​ (transitions directly from solid to gas) at approximately 447°C (837°F). This property is critical for its industrial synthesis, as it allows for easy separation from other furnace byproducts during production.

5. Boiling Point​

Since calcium carbide sublimes rather than boiling, it has no true boiling point. However, its vapor pressure increases significantly above 447°C, leading to decomposition into calcium vapor and carbon before reaching a gaseous state.

6. Additional Physical Properties​

Solubility: Insoluble in water (reacts violently with it instead) and most organic solvents.

Hardness: Mohs hardness of ~4–5 (similar to fluorite), making it brittle and prone to fracturing into smaller pieces.

Thermal Conductivity: Low (≈1.2 W/m·K), typical of non-metallic solids.

 

Practical Implications of Physical Properties​

Storage: Its high density and sublimation point require airtight, heat-resistant containers to prevent moisture ingress and accidental gas release.

Handling: Brittleness necessitates careful packaging to avoid dust generation (powder form is more reactive).

Identification: The grayish-black color and garlic-like odor (when exposed to moisture) help distinguish calcium carbide from other industrial solids.

 

Why Choose ZhenAn Company for High-Purity Calcium Carbide?​

ZhenAn Company supplies calcium carbide with consistent physical properties, tailored to your needs:

Purity: ≥80% CaC₂ (industrial) or ≥95% (food/agricultural), ensuring uniform color and minimal impurities.

Form: Lumps, granules, or powder with customizable particle sizes for optimal density and reactivity.

Packaging: Moisture-proof, durable containers to preserve physical integrity during storage and transport.

 

📧 Contact us at​ info@zaferroalloy.com to learn more about our calcium carbide products and their physical properties!