Potassium chloride is an inorganic chemical compound with the formula KCl. It is an ionic salt consisting of a metal cation (the potassium ion, K+) and a halide anion (the chloride ion, Cl–). It has a white, crystalline appearance and does not have any distinct odor. Potassium chloride is also used as a food additive.
Physical Properties of Potassium Chloride
The molar mass of this compound is 74.5513 grams per mole. It has a density of 1.984 grams per cubic meter. The melting point of potassium chloride corresponds to 1040 K (approximately 767oC). Its boiling point is 1690 Kelvin.
As is the case with most ionic salts, potassium chloride is highly soluble in water. At a temperature of 0oC, the solubility of this compound in water corresponds to 217.1 grams per liter. Any increase in the temperature is accompanied by an increase in solubility. For example, at a temperature of 100oC, the solubility of potassium chloride in water increases to 360.5 grams per liter.
This compound is also soluble in alkalis and glycerol. It is sparingly soluble in alcohols and insoluble in ethers. Potassium chloride crystallizes in a face-centered cubic lattice.
Chemical Properties of Potassium Chloride
The standard molar entropy associated with this compound corresponds to 83 joules per mole Kelvin (J.mol-1K-1). The standard enthalpy of formation of potassium chloride is -436 kilojoules per mole. Its acid dissociation constant (pKa) can be approximated to 7. Metallic potassium can be obtained from this compound by heating it with metallic sodium up to a temperature of 850oC. The chemical equation for this reaction is given by:
KCl + Na ⇌ NaCl + K
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