Standard Molar Enthalpies of Formation of Ce(TCA)_3·3H_2O(s) and Ce(TCA)(C_9H_6NO)_2(s)

The standard molar reaction enthalpies of two reactions,CeCl_3·7H_2O(s)+3CCl_3COOH(s)=Ce(TCA)_3·3H_2O(s)+3HCl(g)+4H_2O(l) (1) and Ce(TCA)_3·3H_2O(s)+2C_9H_7NO(s)= Ce(TCA) (C_9H_6NO)_2 (s)+2CCl_3COOH(s)+ 3H_2O(l) (2),were investigated by classical solution calorimetry and an isoperibol calorimeter at 298.15 K. The standard molar enthalpies Δ_sH _m of solution of CeCl_3·7H_2O(s),3CCl_3COOH(s),Ce(TCA)_3·3H_2O(s),Ce(TCA)_3·3H_2O(s),2C_9H_7NO(s),Ce^(TCA)(C_9H_6NO)_2(s) and 2CCl_3COOH(s) were determined to be (50.615±0.028),(23.431±0.027),(94.206±0.010),(54.151±0.020),(27.485±0.045),(106.392±0.060) and -(14.893±0.026) kJ/mol,respectively. The reaction enthalpies Δ_rH _m of reactions (1) and (2) were obtained to be (204.279±0.023) and -(9.863±0.041) kJ/mol,respectively. According to the above results and the data given in literature,through Hess' law,the standard molar enthalpies Δ_fH _m of formation of Ce(TCA)_3·3H_2O(s) and Ce(TCA)(C_9H_6NO)_2(s) were estimated to be -(3060.0 ±0.087) and -(1369.0±0.292) kJ/mol,respectively.