Equilibrium pressure measurements in the Li-N-H system by static manometric method

✍ Scribed by N.S. Anand; Ram Avtar Jat; S.G. Sawant; S.C. Parida; Ziley Singh Chaudhary; V. Venugopal

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 465 KB
• Volume: 36
• Category: Article
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2010.12.027

✦ Synopsis

The equilibrium pressure over the phase mixture (Li 2 NH þ LiNH 2 þ LiH) was measured from 343 to 683 K by static manometric method. The plot of ln ( p eq /p 0 ) versus (1/T ) showed three distinct temperature regions with different slopes. Analysis of the equilibrium gas composition in each temperature regions revealed that the equilibrium gas is a mixture of H 2 , NH 3 and N 2 below 443 K whereas above 443 K, the equilibrium gas is mainly H 2 . The enthalpy and entropy of the reaction of H 2 with Li 2 NH to form LiNH 2 and LiH are found to be À55.0 AE 1.3 kJ•mol À1 and À86 AE 2 J•K À1 •mol À1 , respectively at 523 K, where LiNH 2 exists in the solid state and À18.5 AE 0.5 kJ•mol À1 and À26 AE 1 J•K À1 •mol À1 , respectively at 658 K, where LiNH 2 exists in the liquid state. The enthalpy and entropy of melting of solid LiNH 2 are calculated as 36.5 AE 1.4 kJ•mol À1 and 60 AE 2 J•K À1 •mol À1 , respectively.