砒酸カルシウムおよび砒酸マグネシウムの熱分解蒸気圧の測定

抄録

he dissociation reactions of both calcium and magnesium arsenates prepared by solid-solid reactions have been examined. The vapour pressure of all gas phases produced by thermal decomposition have been calculated from the results of dew noint measurement. In a similar way the equilibrium constant Kp of the dissociation reactions of both arsenates have been calculated. The results are as follows
1) The calcium arsenate and magnesium arsenate tend to dissociate at the temperature higher than about 1450°C and 1275°C respectively through the following reactions.
3MeO·As₂O₅ (s) =3MeO (s) +1/2As₄O₆ (g) +O₂ (g)....(1)
1/2As₄O₆ (g)=As₂O₃ (g)...(2)
Me: Ca or Mg
2) The relations between log K₂ and 1/T of the (1) reaction are as follows.
3CaO·As₂O₅: log Kp=-42729.4/T+16.870 (1425°-1463°C)
3MgO·As₂O₅: log K₂=-35707.26/T+17.066 (1274°-1353°C)