Calcium chloride dihydrate

Calcium chloride dihydrate is a chemical compound with the formula CaCl2·2H2O. This compound is a hydrated form of calcium chloride (CaCl2), which is a type of salt that is highly soluble in water and is used in various applications ranging from de-icing to food preservation. The dihydrate form means that each formula unit of calcium chloride is associated with two water molecules.

Properties

Calcium chloride dihydrate is characterized by its high solubility in water, which makes it an effective de-icing agent and a desiccant. The presence of two water molecules in its structure contributes to its properties and uses. It has a melting point of 176°C and decomposes before boiling. The compound is also hygroscopic, meaning it can absorb moisture from the air, which is a key feature in its use as a drying agent.

Production

The production of calcium chloride dihydrate typically involves the reaction of limestone (calcium carbonate) with hydrochloric acid: \[CaCO_3 + 2HCl → CaCl_2 + CO_2 + H_2O\] The resulting calcium chloride can then be hydrated to form the dihydrate.

Applications

De-icing and Dust Control

Calcium chloride dihydrate is widely used for de-icing roads, sidewalks, and parking lots due to its ability to lower the freezing point of water. This property helps prevent ice formation and facilitates the melting of ice and snow. It is also used for dust control on unpaved roads and surfaces, as it helps to keep dust particles down by attracting moisture from the air.

Food Industry

In the food industry, calcium chloride dihydrate serves as a firming agent in canned vegetables and in cheese making, where it helps to coagulate the milk, improving the firmness of the cheese.

Medicine

In medicine, calcium chloride dihydrate is used in cardiac resuscitation, acting as an electrolyte replenisher and a counteragent to magnesium intoxication.

Other Uses

Other applications include its use in swimming pool water as a pH buffer and in the oil industry for drilling fluids.

Safety

While calcium chloride dihydrate is generally considered safe for its intended applications, it can cause irritation to the skin, eyes, and respiratory tract upon contact or inhalation of dust. Appropriate safety measures, including the use of personal protective equipment, are recommended when handling the compound.

Environmental Impact

Calcium chloride dihydrate is regarded as environmentally benign in most of its applications. However, excessive use, especially in de-icing, can lead to increased salinity of nearby water bodies, potentially harming aquatic life.