The standard molar enthalpies of formation of β-La2Si2O7and β-Ce2Si2O7

Abstract The standard molar enthalpies of solution of cerium and lanthanum silicates (β-Ce 2 Si 2 O 7 and β-La 2 Si 2 O 7 ) in (6.20 mol·dm -3 HCl + 0.147 mol·dm −3 HF) (aq) were measured. From these values the standard molar enthalpies of formation have been deduced: Δ f H m o (Ce 2 Si 2 O 7 ,cr, β, 298.15 K) = −(3807.6 ± 4.5) kJ·mol −1 and Δ f H m o (La 2 Si 2 O 7 , = −(3815.7 ± 4.5) kJ·mol −1 .