Heat capacity and thermodynamic functions of Na2MoO4 in the temperature range 0-300 K

The heat capacities of two samples of Na2MoO4, prepared by different methods, were measured at low temperatures. Obtained C-p(o) data differ significantly (from 3 to 7% at temperatures 50-300K) from literature ones. Smoothed values of thermodynamic functions (heat capacity, entropy, change of enthalpy and Gibbs energy) were calculated in the temperature range 0-300 K. At temperature 298.15 K standard values are: C-p(o)(298.15 K) = 132.2 +/- 0.2 J K-1 mol(-1), H-degrees(298.15 K) = 149.9 +/- 0.2 J K-1 mol(-1), H-degrees(298.15 K) - H-degrees(0 K) = 23.82 +/- 0.02 kJ mol(-1), phi degrees (298.15 K) = 69.98 +/- 0.24JK(-1)mol(-1). Refined values of sodium molybdate entropy of formation and Gibbs energy of formation are: Delta S-r(degrees)(Na2MoO4,298.15K)=-391.39 0.60JK(-1)mol(-1) and Delta(f)G(degrees)(Na2MoO4,298.15K)=-1351.0 1.3kJmol(-1), relatively. (C) 2007 Elsevier B.V. All rights reserved.