The standard molar enthalpies of formation of Pb2Cro5(s) and Pb5CrO8(s) by acid solution calorimetry

The standard molar enthalpies of formation, Delta H-f degrees(m) (298.15 K) of Pb2CrO5(s) and Pb5CrO8(s) were determined using an isoperibol calorimeter. The enthalpies of solution of pure compounds, viz., Pb2CrO5(s), and Pb5CrO8(s) as well as mixtures viz., (PbCrO4(s)+ PbO(s)) and (PbCrO4(s) + 4PbO(s)) in HNO3 (aq., 8 mol . dm(-3)) at T = 298.15 K were measured. Using these values, Delta H-f degrees(m) (298.15 K) of Pb2CrO5(s) and Pb5CrO8(s) were determined as -(1171.5 +/- 1.7) kJ . mol(-1) and -(1850.6 +/- 8.7)kJ . mol(-1), respectively. (C) 2011 Elsevier Ltd. All rights reserved.