Investigation on the thermal behaviour of Mg(NO₃)₂·6H₂O I. The decomposition behaviour

The decomposition mechanism of Mg(NO3)2·6H2O was studied by means of simultaneous TG, DTG and DTA method combined with EGA technique under conventional and quasi isothermal-quasi isobaric conditions. It has been found that Mg(NO3)2·6H2O melts at 89 °C in a congruent way. The solution formed begins to boil at 147 °C. The water loss process of the salt hydrate and the decomposition process of the Mg(NO3)2 always overlap to some extent. Accordingly, Mg(NO3)2 of stoichiometric composition cannot be prepared thermally, because the compound always contains some basic salt. The last part of water departs in the vicinity of 270 °C with extreme rapidity. In contrast to expectations the compound decomposes in pure “self-generated” atmosphere at a temperature lower by about 80 °C than in the presence of air which contains a small amount of the gaseous decomposition product.