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Physical & Chemical properties

Endpoint summary

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Description of key information

Calcium carbide is an inorganic solid; the sample analyzed consisted of powder and crude granules.

The melting point of the substance is 2300 °C.

The substance has a density of 2.22 g/cm³.

The particle size distribution of calcium carbide was determined by laser diffraction. The resulting mass median diameter (D50, mean of three determinations) is 30.11 µm, the corresponding D10 value was determined to be 4.50 µm.

The vapour pressure of calcium carbide is reported to be 1.32E-033 mm Hg at 25°C.

The partition coefficient is not applicable to calcium carbide as the substance is inorganic and it hydrolyses very fast to Ca(OH)2 and acetylene. Ca(OH)2 is as well inorganic, hence the partition coefficient is not applicable. The experimental logKow of acetylene is 0.37.

Due to the rapid decomposition water solubility of Calcium Carbide itself cannot be determined. Solubility of 1200 mg/l is given based on the degradation products Ca(OH)2 and C2H2.

Surface tension is waived, because it isn't a desired property

Flashpoint is waived because it is an inorganic substance.

The self-ignition temperature of the substance is 390 °C.

Dry calcium carbide is not highly flammable. However, in contact with water/moisture the substance instantly decomposes hydrolytically, yielding calcium hydroxide and the extremely flammable gas acetylene. Thus, the water solubility for calcium carbide cannot be measured and the chemical safety assessment is based on the relevant decomposition product. Calcium hydroxide is not considered as a relevant breakdown product since the main effect on environmental media is a pH shift which is readily compensated in the environment due to the buffering capacity of natural waters, sediments and soils, and due to the neutralising reaction with carbon dioxide. The relevant degradation product therefore is acetylene, a gaseous substance. The water solubility of acetylene is 1200 mg/L at 20 °C and pH 7, the vapour pressure is 40400 mm Hg at 25 °C, and its log Kow is 0.37.

Calcium carbide is not explosive, nor is it sensitive to thermal influence, shock, or friction.

Calcium Carbide is considered not oxidizing based on the chemical structure.

Due to the degradation of calcium carbide to calcium hydroxide upon contact with water, aqueous solutions show an alkaline pH (pH 12.48 in 1 % (w/v) solution).

Additional information