1.For which of the following pairs indicate which substance is expected to be:
(a)More covalent ZnO or ZnS
參考答案:
ZnS
硫離子半徑較大，造成陰陽離子尺寸較接近，應該more ionic才對吧？奇怪？
2.By extrapolation from known data for Cr, W, and Mo, Seaborg estimated the
following emf values for the couples involving
-0.5 -0.2 -0.7 0.0
Ea。 MO3 → M2O5 → MO2 → M3+ → M
Predict the results of the following.
(a)M is placed in 1M HCl.
(b)MCl3 is placed in an acidic solution containing FeSO4.
(c)MO2 and MO3 are in contact in acidic solution.
(d)M3+ and MO3 are in contact in acidic soultion.
(e)M is treated with excess concentrated HNO3
參考答案:
(a)No reaction occurs. E。=0.0 for the evolution of H2 with the
formation of M3+ , therefore, overvoltage effects would be
sufficient to prevent this reaction.
(b)2M+ +3H2O+SO2-→2MO2+H2SO3+4H+ E。=0.87V
(c)No recation.(E。=-0.3 for MO2+MO3→M2O5)
(d)2M3+ +MO3+3H2O→3MO2+6H+ E。=0.35V
(e)M+2MHNO3→MO3+2NO+H2O E。=0.72V
我的疑問是(b)~(e)的電位是如何計算出來的？用 Nerst equation嗎？可是沒有給離子
濃度？謝謝。
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