Chemical reactions between salts dissolved in liquid lithium: reaction of lithium nitride, Li3N, with dilithium acetylide, Li2C2 , to form the dilithium salt of cyanamide, Li2NCN, in the metal.
1979; Elsevier BV; Volume: 85-86; Linguagem: Inglês
10.1016/0022-3115(79)90506-3
ISSN1873-4820
AutoresR. J. Pulham, Peter Hubberstey, Michael G. Down, Anne E. Thunder,
Tópico(s)Ammonia Synthesis and Nitrogen Reduction
ResumoAbstract The relatively large solubility of Li3N in liquid Li at moderate temperatures, log10 (mol fraction N) = 1.168 – 2036T−1 where 473⩽T ⩽708 and T = (273 + θ°C), and the large increase in the electrical resistivity (7.0 × 10−8ωm/mol%N) that the salt confers on the metal, make it possible to study the chemical reactions of this solute relatively easily and accurately. Thus changes in resistivity show that dissolved Li3N does not react with LiH in Li and no LiNH2 is formed, with Li2C2, however, dissolved Li3N reacts to form the dilithium salt of cyanamide, Li2NCN, which is crystallized and isolated by evaporation of the metal. Li2NCN is tetragonal with a = b = 3.687(3), c = 8.668(5)A, and space group I4/mmm. Each Li+ ion is tetrahedrally coordinated by parallel centrosymmetric NCN−−ions, and each anion is surrounded by eight cations. Unlike most salts which contain heteroatomic anions, this compound is stable towards lithium and has a standard enthalpy of formation at least as negative as −359.5 kj/mol. The changes in resistivity of the metallic solution during reaction show plainly the association between N−−− and C2−− and are not inconsistent with the formation of an intermediate CN4−− species. The implications of the behaviour of Li3N in Li towards LiH and Li2C2 on Li purification and metal corrosion aspects of reactor technology are discussed.
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