Study of transition temperature through mixed crystal formation. III. Orthorhombic zinc sulphate and magnesium sulphate

Abstract

Distribution studies with orthorhombic zinc sulphate and magnesium sulphate as hosts and ⁵⁴Mn as guest have been carried out in order to determine the transition temperatures of different phases. The change in morphology of either the host or the guest is always indicated by a prominent change in distribution values at the point of transition. In the present study, with zinc sulphate as host and ⁵⁴Mn as guest, the transition temperatures of the two components, orthorhombic MnSO₄,7H₂O and MnSO₄,6H₂O, were found to be 10° and 42.5°C respectively. The host component ZnSO₄,7H₂O transforms to its lower hydrate ZnSO₄,6H₂O at 38.95°C. Distribution studies with MgSO₄,7H₂O as host and ⁵⁴Mn tracer as guest also confirm that MnSO₄,6H₂O undergoes transition at 42.5°C. Isolation of MnSO₄,6H₂O in finite concentration has been achieved by cocrystallizing with stable and well defined ZnSO₄,6H₂O at 42°C.