Standard gibbs energies of formation of the carbides of vanadium by emf measurements

The relative partial molar Gibbs energies of vanadium in the vanadium-carbon system have been determined for the V-C alloys containing 36.7, 41.2, 43.1, 44.8, 45.5, 46.8, 50.5, and 54.0 at. pct carbon by using galvanic cells of the type (−) V, VF₃, CaF₂ // CaF₂ // CaF₂, VF₃, ‘V-C’ (+) The measurements were carried out in the temperature range of 816 to 1008 K. The relative partial molar Gibbs energies of carbon have been calculated in the same composition range. The relative integral molar Gibbs energy in the VC single-phase region can be expressed asG ^M = −98,850 + 72,242X_C + (24.81 −37.23X _C)TJ/mol The standard Gibbs energies of formation of V₄C_3-x and V₂CC can be represented as ΔG° = −67,208 + 9.37T J/mol of V_0.60C_0.40 and ΔGδ = −62,581 + 7.10T J/mol of Va66Co.34 respectively.