Crystal Hydrates

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Crystal Hydrates

 

crystals containing molecules of water.

Many salts, acids, and bases are precipitated from aqueous solutions in the form of crystal hydrates. Many naturally occurring minerals, such as gypsum (CaSC4·2H2O) and carnallite (MgCl2·KCl·6H2O), are examples of typical crystal hydrates. The water of crystallization can usually be removed by heating. This is often accompanied by the stepwise decomposition of the crystal hydrate. For example, blue vitriol CuSO4·5H2O (dark blue) is converted to CuSO4·3H2O (light blue) and CuSO4·H2O (white) at temperatures above 105°C, and its complete dehydration takes place above 250°C. However, certain compounds (for example, BeC2C2O4·H2O) are stable only as crystal hydrates and cannot undergo dehydration without decomposing.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The main crystal hydrates of GP samples are similar to those of PC paste, that is, Ca(OH)2 (CH), calcium aluminate hydrate (CAH), and unreacted clinker, because the main chemical compositions of GP and cement are similar.