Basic Magnesium Chlorides

A study of the system magnesium oxide-magnesium chloride-water and the heat of formation of magnesium oxychloride

“…The results of X-ray examination of the precipitates are given in table 1. Except in three instances, the final precipitates were Mg(OH)!…”

“…The author believes that the oxychloride as precipita ted con ta ins 8 molecules of water in agr eem ent with th e composition 2MgO ·HCJ..5HzO (equivalent to 3Mg (OH)z-MgCI2·8H 20 ) given by Robinson and Waggaman [1] from analyses of unwashed precipitates and of the solu tions in which they formed. (Their reported composition 3YIgO·MgC12·rOH20 seems to be erroneously converted from their determined composition of 2.· 02MgO.HC1·5.04H20. )…”

“…The h eats of reaction between Mg(OHM c) (brLlcitr) . M gCI2·6H 20 (c) and H 20 (1) to form the oxychlor ides were calculated from the observed heats of solu lion and applied with the heats of formation of those reactants [8] to calculate the he ats of formation of the oxychloricles. P ertinrn t data and th e calculated res ults arc included in table 5.…”

“…Robinson and W"aggaman [1] 1, Lukens [2] , Chassevent [3], Bury and Davies [4], F eitknecht [5], F eitkn echt and H eld [6], and others have iden tifi ed the t hree solid ph ases occurring at room temp erature as Mg(OH)z, 5Mg(OH)z·MgCI2·nH zO, and3Mg(OH)z·M gCb·nH zO.…”

“…This equation is the s um of the following equations: 0.99211!JgO (c, finely divided) + 0.9921H20 (1) = 0.9921Mg (OH)2(c), AH1= -9.656 kcal 0.5510Mg (OHM c) + 0.1102 (MgC12·6H20 ) (c) + 0.2204H20(l) = 0.1l02 (5Mg (OHh 1{gC12·81-120 ) (c), AH2 = -0.986 k cal 0.1l02MgC12(c) + 0.6612H20(l) = 0.1l02 (~lgC12 · 6H20.…”