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Synthesis, Characteristics and Standard Molar Enthalpies of Formation of MZn 2 HPO 4 PO 4 (M=Na + , K + )
Author(s) -
YUAN AiQun,
WU Jian,
HUANG ZaiYin,
WU Kun,
SONG BaoLing,
LIAO Sen,
TONG ZhangFa
Publication year - 2008
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.200890220
Subject(s) - chemistry , standard enthalpy of formation , triclinic crystal system , decomposition , dissolution , molar ratio , thermochemical cycle , solid state , analytical chemistry (journal) , nuclear chemistry , crystallography , crystal structure , organic chemistry , hydrogen , hydrogen production , catalysis
MZn 2 HPO 4 PO 4 (M=Na + , K + ) double salts were synthesized by a solid‐state reaction at low temperature and a hydrothermal method, respectively, and characterized by XRD, FT‐IR, TG and SEM. Thermochemical study was performed by an isoperibol solution calorimeter. According to Hess's law, a new thermochemical cycle was designed. The results show that the obtained products are layered compounds with an isostructure of triclinic system. The decomposition temperatures are 415 and 430 °C by TG, respectively. With the dissolution enthalpies and other standard chemical data, the standard molar formation enthalpies of the MZn 2 HPO 4 PO 4 (M=Na + , K + ) were worked out as follows: = f H ⊖ m [NaZn 2 HPO 4 PO 4, s] =(−3042.38±0.31) kJ·mol −1 and = f H ⊖ m [KZn 2 HPO 4 PO 4, s] =(−3093.46±0.27) kJ·mol −1 .