The difference between anhydrous calcium chloride and dihydrate calcium chloride

The core difference between anhydrous calcium chloride (CaCl ₂) and dihydrate calcium chloride (CaCl ₂ · 2H ₂ O) lies in the content of crystal water, physical form, purity, and application. The specific differences are as follows:

Chemical composition and form of existence: Anhydrous calcium chloride does not contain crystalline water, with the chemical formula CaCl ₂; Dihydrate calcium chloride contains two crystalline water molecules, with the chemical formula CaCl ₂ · 2H ₂ O

Physical appearance: Anhydrous calcium chloride appears as white spherical or powdery particles (diameter 2-6 millimeters) with a porous surface; Calcium chloride dihydrate is a white plate-like crystal (1-2 millimeters thick) with a smooth surface. ‌‌

Net content of calcium chloride: Anhydrous calcium chloride has a higher purity (90-94%), while dihydrate calcium chloride has a lower content (about 70%). ‌‌

Main purpose:

Anhydrous calcium chloride: Strong hygroscopicity, suitable for dry gases (such as nitrogen, oxygen) or liquids, as well as high-precision dehydrating agents. ‌‌‌

Dihydrate calcium chloride: has weak hygroscopicity and is commonly used as a snow melting agent, refrigerant (with a freezing point as low as -30 ℃), and building antifreeze. ‌‌