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

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 42.5C respectively. The host component ZnSO4,7H2O transforms to its lower hydrate ZnSO4,6H2O at 38.95C. Distribution studies with MgSO4,7H2O as host and 54Mn tracer as guest also confirm that MnSO4,6H2O undergoes transition at 42.5C. Isolation of MnSO4,6H2O in finite concentration has been achieved by cocrystallizing with stable and well defined ZnSO4,6H2O at 42C.