Potassium hydrogencarbonate

Endpoint summary

Additional information

Potassium hydrogencarbonate is a colourless, transparent crystal or white powder with a monoclinic structure. When heated above 100°C, it begins to decompose into K₂CO₃, H₂O, and CO2. The boiling point of potassium hydrogencarbonate can not be determined due to decomposition.Three peer-reviewed sources report the density of potassium hydrogencarbonate to be 2.17 g/cm³ at 20°C. For potassium hydrogencarbonate the particle sizes distribution is as follows (for one example): Particles > 0.850 mm (max 0.1 – 0.2 w/w%), > 0.500(4 – 20 w/w%), > 0.250 (max 50 - 75 w/w%), and > 0.100 (min 85 w/w%).The available data for particle size distribution are sufficient and adequate for the purpose of classification and labelling and/or risk assessment. In an inhalation study with very fine ground potassium hydrogencarbonate with 25% of the particles < 0.001 mm and 25% < 0.003 mm,no effects were observed.The determination of the vapour pressure of potassium hydrogencarbonate is technically not feasible, since the substance decomposes above 100°C.The water solubility of potassium hydrogencarbonate is 362 g/L at 25°C. According to the classification, potassium hydrogencarbonate can be regarded as very soluble in water.Potassium hydrogencarbonate is not soluble in ethanol. The substance dissociates in water completely to K⁺and inorganic carbon (CO₃^2-ions in equilibrium with HCO₃^-and CO2). The dissociation constants of CO2 in water systems are 6.35 (pK1) and 10.33 (pK2) at 25°C in fresh water and 5.86 (pK1) and 8.95 (pK2) at 25°C in seawater (CO2(solv) + H2O <=> H2CO3=> HCO₃^-=> CO₃^2-).The pH of am 0.1 M aqueous solution of potassium hydrogencarbonate is reported to be 8.2.