WATER-VAPOR PRESSURE AND THERMODYNAMICS OF THE DEHYDRATION OF MANGANESE, NICKEL, CADMIUM, AND LEAD PERCHLORATE HYDRATES

The water-vapor pressure has been measured by a static method, the tem perature limits for existence have been determined, and the parameters of the equation lgp [Torr] = b - a/T have been calculated for the fol lowing crystal hydrates: Mn(ClO4)2 . 2H2O (90-130-degrees-c a = 3527.0 , b = 8.487), Ni(ClO4)2.4H2O (60-100-degrees-C, a = 3606.7, b = 9.704) , Ni(ClO4)2.2H2O (110-160-degrees-C, a = 4261.7, b = 10.103), Cd(ClO4) 2.6H2O (25-58.2-degrees-C, a = 3143.7, b = 9.356), Cd(ClO4)2.2H2O (90- 144.8-degrees-C, a = 3823.3, b = 9.472), Pb(ClO4)2.3H2O (10-47-degrees -C, a = 2932.9, b = 9.391 and 47-81.5-degrees-C, a = 2448.1, b = 7.877 ), Pb(ClO4)2.H2O (60-102.4-degrees-C, a = 3610.2, b = 9.857). A hither to unknown metastable hydrate Cd(ClO4)2.4H2O with a phase transition a t 30.9-degrees-C (20-30.9-degrees-C, a = 3669.5, b 11.343 and 30.9-63. 7-degrees-C, a = 3058.6, b = 9.339) has been detected.