Direct Determination of Standard Gibbs Energies of the Formation of 4CaO center dot P2O5 and 3CaO center dot P2O5 by Transpiration Method

作者：Yamasue Eiji^*; Shimizu Kenji; Nagata Kazuhiro

来源：ISIJ International, 2013, 53(10): 1828-1835.

DOI：10.2355/isijinternational.53.1828

• calcium phosphate
• transpiration method
• phosphorus
• thermodynamics
• standard Gibbs energy

The standard Gibbs energy changes of the following reactions have been measured by using transpiration method; %26lt;br%26gt;4CaO center dot P2O5(s)+5C(s)=4CaO(s)+P-2(g)+5CO(g) %26lt;br%26gt;Delta G degrees/kJ=1623.6-0953T(+/- 2.7), (1373%26lt;T/K%26lt;1573) %26lt;br%26gt;4(3CaOxP(2)O(5))(s)+5C(s)=3(4CaO center dot P2O5)(s)+P-2(g)+5CO(g) %26lt;br%26gt;Delta G degrees/kJ=1946.4-1.193T(+/- 0.9), (1448%26lt;T/K%26lt;1523) %26lt;br%26gt;The standard Gibbs energies of the formation of 4CaO center dot P2O5 (Delta G(f)degrees,((4CaO center dot P2O5))) and 3CaO center dot P2O5 (Delta G(f)degrees,((3CaO center dot P2O5))) have been derived as follows; %26lt;br%26gt;Delta G(f)degrees((4CaO center dot P2O5))/kJmol(-1)=-4765.4+0.965T, (1373%26lt;T/K1573) %26lt;br%26gt;Delta G(f)degrees((3CaO center dot P2O5))/kJmol(-1)=-4200.1+0.912T, (1448%26lt;T/K%26lt;1523) %26lt;br%26gt;The reasons for discrepancies from reported values were discussed from the view point of whether the activity of phosphorus is measured directly or not.

• 出版日期2013