Calcium chloride dihydrate
[CAS# 10035-04-8]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Metal halides and halides >> Metal chlorides and salts
• Name: Calcium chloride dihydrate
• Molecular Formula: CaCl₂.2(H₂O)
• Molecular Weight: 147.02
• CAS Registry Number: 10035-04-8
• EC Number: 600-075-5
• SMILES: O.O.[Cl-].[Cl-].[Ca+2]

Properties

• Density: 0.835
• Melting point: 175 °C
• Water solubility: 1000 g/L (0 °C)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H319
• Safety Statements: P264+P265-P280-P305+P351+P338-P337+P317

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H302
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	4	H332
Acute toxicity	Acute Tox.	4	H312

Discovery and Applications

Calcium chloride dihydrate (CaCl₂·2H₂O) is a widely used chemical compound known for its hygroscopic nature and versatility in various industrial and commercial applications. It is the hydrated form of calcium chloride, consisting of two water molecules bound to each calcium chloride unit. This compound has been a subject of interest since its discovery due to its ability to absorb moisture, making it a valuable substance in numerous processes requiring desiccation, deicing, and chemical synthesis.

The history of calcium chloride can be traced back to early chemical investigations into salts and their properties. Calcium chloride dihydrate is typically derived from natural brine deposits or produced as a byproduct in the Solvay process, where sodium carbonate is manufactured. Through a crystallization process, calcium chloride is purified and hydrated to form the dihydrate, a more stable and commonly used form. The compound is available in granular or flake form, depending on the specific industrial needs.

One of the most prominent applications of calcium chloride dihydrate is in deicing and dust control. Its ability to lower the freezing point of water makes it highly effective in preventing ice formation on roads, sidewalks, and other surfaces. In regions that experience heavy snowfall, calcium chloride dihydrate is often used as an efficient ice melt. Its hygroscopic properties allow it to attract moisture from the atmosphere, which facilitates the melting of ice even at lower temperatures compared to other deicing agents like sodium chloride.

Calcium chloride dihydrate also plays a significant role in the food industry. It is commonly used as a firming agent in food products such as canned vegetables and tofu, where it helps maintain texture and structural integrity during processing. In cheese making, calcium chloride dihydrate is added to milk to improve the coagulation process, enhancing the yield and quality of the final product. Its use in the food industry is regulated, and it is considered safe for consumption at appropriate levels.

In the construction industry, calcium chloride dihydrate serves as an additive in concrete formulations. When added to cement, it accelerates the hydration process, reducing the setting time of concrete. This is particularly useful in cold weather conditions where the curing process is slower. The use of calcium chloride dihydrate in construction improves the workability of concrete and enhances its strength by promoting faster hydration reactions.

Calcium chloride dihydrate is also valuable in the chemical industry, where it functions as a desiccant. Its strong affinity for water allows it to be used in drying gases and liquids. It is commonly employed in laboratory and industrial settings for moisture control, ensuring that reactions occur under anhydrous conditions. The compound's desiccating properties extend to its use in refrigeration systems, where it serves as a brine solution for cooling processes.

In the field of medicine, calcium chloride dihydrate is utilized for its role in maintaining electrolyte balance. It is administered intravenously in medical emergencies to treat calcium deficiencies, hyperkalemia, or certain cardiac conditions. Calcium ions are crucial for various physiological processes, including muscle contraction and blood coagulation, making calcium chloride an essential therapeutic agent in critical care.

Environmental considerations have also driven research into the effects of calcium chloride dihydrate on ecosystems. While it is widely used for deicing, studies have been conducted to assess its impact on soil and water systems, particularly in areas where large quantities are applied. Research suggests that the compound can alter the chemical composition of soil and water, leading to potential environmental concerns, which have prompted the development of guidelines for its responsible use.

In conclusion, calcium chloride dihydrate is a versatile chemical compound with a broad range of applications across various industries. Its hygroscopic nature and effectiveness in moisture control, deicing, and food processing make it a valuable substance. As research into its environmental effects continues, the compound's role in industrial and commercial processes remains significant, contributing to advances in numerous fields.

References

2018. The Chemical and Products Database, a resource for exposure-relevant data on chemicals in consumer products, Scientific Data, volume 5, Article number: 180125,
DOI: 10.1038/sdata.2018.125