CBSE Class 11-science Answered

Magnesium chloride is very soluble in water, and crystallizes there from as a hexahydrate, MgC₁₂.6HO₂, which is deliquescent. The latter substance, containing about 53% water, cannot be dehydrated further by simple heating without substantially complete decomposition, the basic salt Mg₂OC₁₂ and the hydroxide Mg(OH)₂ being formed with the liberation of hydrochloric acid.

The dehydration of normal hydrated magnesium chloride, is attended with numerous difficulties due to the great tendency toward decomposition with formation of basic magnesium chloride, or oxide, and hydrochloric acid. Special precautions must be taken to prevent, or at least to minimize, such decomposition in order to obtain a satisfactory product.