Commercial calcium chloride is mainly synthesized with three manufacturing processes as follows:
Ammonia-soda process
CaCl2 is a by-product in the production of sodium carbonate. The process is also called Solvay process in which the reaction between sodium chloride (salt brine) with calcium carbonate (limestone), and ammonia as a catalyst (1):
2 NaCl + CaCO3 → CaCl2 + Na2CO3
Limestone-hydrochloric acid Process
React hydrochloric acid with calcium carbonate (limestone).
2HCl + CaCO3 → CaCl2 + H2O + CO2
Natural brine process
Purification of naturally-occurring brines (such as salt lakes) by removing magnesium with adding Ca(OH)2, and precipitating sodium chloride by increasing the concentration of CaCl2.
Specification
Two types
According to the different amount of crystalline water, calcium chloride can be divided into two types:
Dihydrate: the main type in the market for deicing and dust control.
Anhydrous: commonly as a drying agent for gases and liquids. It can attract 6 times moisture: CaCl2 + 6H2O → CaCl2 · 6H2O
Also with hexahydrate form, but seldom in the market.
CaCl2 can also be classified into food and industrial grades based on the different uses.
Other names
Calcium dichloride
Calcium (II) chloride
Calcium chloride anhydrous or dihydrate
CAS number
10035-04-8 (dihydrate)
10043-52-4 (anhydrous)
Chemical formula
CaCl2 (anhydrous)
CaCl2 · 2H2O (dihydrate)
CaCl2 · 6H2O (hexahydrate)
Molecular weight
110.99 (anhydrous)
147.02 (dihydrate)
Properties
Appearance
White, odourless, both hygroscopic and deliquescent (converts to a liquid brine after absorbing enough moisture). It is supplied in the form of powder/pellet/flake/granular or solution depending on the requirements of the application.
Solubility
Highly soluble in water with the solubility 1g/1.5ml at 25°C and soluble in ethanol. It dissociates calcium ion and chloride ion when dissolved in water with the following equation: CaCl2 (aq) → Ca2+ (aq) + 2Cl– (aq)
Reactions
CaCl2 is commonly reacts with the below ingredients and with the chemical reactions:
Sodium carbonate: CaCl2 + Na2CO3 → CaCO3 + 2NaCl
Sodium bicarbonate : CaCl2 + 2NaHCO3 → CaCO3 + 2NaCl + H2O + CO2
Potassium carbonate: CaCl2 + K2CO3 → CaCO3 + 2KCl
Sodium phosphate : CaCl2 + Na3PO4 → Ca3(PO4)2 + NaCl
Sodium hydroxide: CaCl2 + 2NaOH → Ca(OH)2 + 2NaCl
