MASS-SPECTROMETRIC STUDY ON THE FORMATION OF LIOD (G) BY REACTION OF LI4SIO4 (CR) WITH D2O (G) OR D2 (G)

A mass spectrometric study of the reactions of D2O and D2 with Li4SiO4, which both lead to the formation of LiOD, was initiated in the range of pressures and temperatures close to those anticipated in blanket design. Li4SiO4 (cr)+D2O (g)=Li2SiO3(cr)+2LiOD(g)describes the formation of LiOD from deuterium oxide vapor. From the equilibrium constant K for this reaction given by K = p2(LiOD) a(Li2SiO3)/p(D2O) a(Li4SiO4) a third law heat of reaction of DELTA(r)H0 (298.15 K) = (469.2+/-10.0) kJ/mol was calculated. The equilibrium constant corresponding to the reaction of Li4SiO4 with D2 yields a third law heat of reaction of DELTA(r)H0 (298.15 K) = (475.5 +/- 15) kJ/mol.