SOLUBLE COMPLEXES IN THE SYSTEMS DICALCIUM PHOSPHATE DIHYDRATE OR DIMAGNESIUM PHOSPHATE TRIHYDRATE EQUILIBRATED WITH AQUEOUS SALT SOLUTIONS

摘要

Dicalciumphosphatedihydrate(CaHPO4a??2H2O)(DCPD)ordimagnesiumphosphatetrihydrate(MgHPO4a??3H2O)(DMPT)wasequilibratedwithwateroraqueoussolutionsofCaCl2,CaSO4,MgCl2,MgSO4,KClorK2SO4at25a€??±a€?1a€?Cfor24a€?hr.ValuesofpCaa€?+a€?pHPO4andpMga€?+a€?pHPO4correctedforcomplexformation,usingdissociationconstantspublishedforCaHPO4,MgHPO4,CaSO4andMgSO4solublecomplexes,werecalculated.TheaveragecorrectedvalueofpCaa€?+a€?pHPO4a€?=a€?6.68a€??±a€?0.03,calculatedforthesystemsinwhichDCPDwasequilibratedwithwateroraqueousCaCl2,CaSO4,KClorK2SO4,waslargerthanpCaa€?+a€?pHPO4a€?=a€?pKDCPDa€?=a€?0.36at25a€?Ccalculatedassuminganabsenceofsolublecomplexes.However,itshowedexcellentagreementwithpKDCPDa€?=a€?6.66a€??±a€?0.02at37.5a€?CcalculatedassumingCaH2PO4+andCaHPO4complexestobepresent.TheaveragecorrectedvalueofpMga€?+a€?pHPO4a€?=a€?5.82a€??±a€?0.01,calculatedforthesystemsinwhichDMPTwasequilibratedwithwateroraqueousMgCl2,MgSO4,KClorK2SO4showedexcellentagreementwithpMga€?+a€?...