Standard Free Energies for Formation of Iron Oxides and Other Metal Oxides.

GOTO Kazuhiro, MATSUSHITA Yukio

doi:10.2355/tetsutohagane1955.50.8_1167

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Other Title

鉄酸化物ほか各種金属酸化物の標準生成自由エネルギー
鉄酸化物ほか各種金属酸化物の標準生成自由エネルギー高温における酸素濃淡電池の研究-3-
テツサンカブツホカカクシュキンゾクサンカブツノヒョウジュンセイセイジユウエネルギーコウオンニオケルサンソノウタンデンチノケンキュウ 3
高温における酸素濃淡電池の研究-III
Study on oxygen concentration cells at high temperature-III

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The standard free energies for formation of several metal oxides were determined by electromotive force measurements of reversible oxygen concentration cells. Zircorria, stabilized with calcium oxide, was used as the electrolyte, which performed as a pure anion conductor due to the movement of oxygen lattice defects at high temperature above 500°C. The measurement has been carried out extensively on many different structures of the cells, including the cells with four electrodes. The obtained results are as follows: (1) Fe(α)+1/2O₂(G)=FeO(s) ΔG°_f=57, 610+14.13T(°C)±300Cal (500°C-up to transformation point of α→γiron) (2) 3Fe(α)+2O₂(G)=Fe₃O₄(s) ΔG°_f=-236, 600+63.33T(°C)±1000Cal (500°C-up to transformation point of α→γiron) (3) Pb(l)+1/2O₂(G)=PbO(S. or l) ΔG°_f=-45, 710+23.47T(°C)±100Cal (500°C-M.P. of PbO) ΔG°_f=-40, 840+17.82T(°C)±100Cal(M.P. of PbO-1150°C) (4) Sn(l)+1/2O₂(G)=SaO(s) ΔG°_f=-61, 000+23.72T(°C)±50Cal (500°C-1100°C) (5) Cu(s)+1/2O₂(G)=CaO(s) ΔG°_f=33, 640+23.66T(°C)±300Cal (500°C-900°C) (6) 2Cu(s)+1/2O₂(G)=Cu₂O(s) ΔG°_f=-35, 360+16.98T(°C)±100Cal (500°C-M.P. of Cu) (7) 2Ta(s)+5/2O₂(G)=Ta₂O₆(s) ΔG°_f=-413, 800+70.66T(°C)±300Cal (800°C-1200°C) The accuracy of the above data was discussed in comparison with the previous data. Also, the reversibility, and polarization effects of the cells were discussed.

Journal

Tetsu-to-Hagane

Tetsu-to-Hagane 50 (8), 1167-1175, 1964

The Iron and Steel Institute of Japan

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