HIGH-TEMPERATURE THERMAL-PROPERTIES OF KH2PO4 - PHASE-TRANSITIONS AND DECOMPOSITIONS

被引：16

作者：

BROWN, ME ^{[1
]}

GLASSER, L ^{[1
]}

LARSON, J ^{[1
]}

机构：

[1] RHODES UNIV,DEPT CHEM,GRAHAMSTOWN 6140,SOUTH AFRICA

来源：

THERMOCHIMICA ACTA | 1979年 / 30卷 / 1-2期

关键词：

D O I：

10.1016/0040-6031(79)85057-1

中图分类号：

O414.1 [热力学];

学科分类号：

摘要：

Phase transitions and the thermal decomposition of KH2PO4 have been examined from room temperature to above 300°C by means of hot-stage microscopy, isothermal gravimetry and differential scanning calorimetry. Phase transitions at 198 and 242°C are confirmed, with corresponding enthalpy changes 4.2 and 2.3 kJ mole-1, but no evidence has been found of a transition reported near 110°C. The thermodynamic and other evidence suggest a structural change at 198°C while the change at 242°C is less profound, perhaps involving only changes in the form of the hydrogen bonding. Thermal decomposition occurs in four stages, under conditions of free vapour escape, with the loss of one-quarter of a mole of water per formula unit of KH2PO4 in each stage. The products of each stage of decomposition are tentatively identified. © 1979.

引用

页码：233 / 246

页数：14

共 39 条

[1] NMR PROTON SECOND MOMENTS IN KH2PO4-TYPE CRYSTALS [J].