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kane97
4th April 2017 14:41

Ai giúp mình vs! thank
Reaction 1. 2H+ + 2e–
= H2 E o— = 0.000 V SHE.
Reaction 2. O2 + 2H+ + 2e–
= H2O E o— = + 1.228 V SHE.
Note that Reaction 2 is an alternative form of the equation introduced
earlier:
O2 + H2O + 2e–
= 2OH–
but re-written in terms of H+ ions instead of OH–
ions, to permit plotting
on the potential-pH diagram. The gases are evolved against atmospheric
pressure, so that aH2
= aO2
= 1.
Application of the Nernst equatio... Ai giúp mình vs! thank
Reaction 1. 2H+ + 2e–
= H2 E o— = 0.000 V SHE.
Reaction 2. O2 + 2H+ + 2e–
= H2O E o— = + 1.228 V SHE.
Note that Reaction 2 is an alternative form of the equation introduced
earlier:
O2 + H2O + 2e–
= 2OH–
but re-written in terms of H+ ions instead of OH–
ions, to permit plotting
on the potential-pH diagram. The gases are evolved against atmospheric
pressure, so that aH2
= aO2
= 1.
Application of the Nernst equation yields:
Reaction 1. E = 0.000 – · log
= – 0.0591 pH (3.26)
—————–––
Reaction 2. E = + 1.228 – · log
= 1.228 – 0.0591 pH (3.27)
––––––––––––––––––––
Equations 3.26 and 3.27 are superimposed as dotted lines on Figure 3.2.
The two lines enclose a domain within which water is stable. For combinations
of potential and pH above the top line, water is unstable and decomposes
evolving oxygen. For combinations below the bottom line, it is also
unstable and decomposes evolving hydrogen.
3.1.5.4 Application of Pourbaix Diagrams to Corrosion Problems
The first requirement is to select the appropriate lines from the Pourbaix
diagram. An internationally agreed convention is adopted in which a
metal is considered to be actively corroding if the equilibrium activity of a
soluble ion derived from it, e.g., aFe2+ or aFe3+ exceeds 10–6. For clarity, the
diagram for aFe2+ = aFe3+ = 10–6, selected from Figure 3.2, is given in
Figure 3.3.
As explained later in discussing kinetics, a metal exposed to an aqueous
medium acquires a potential from coupled electrode processes such as
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- Huy Quang đêm qua e xem câu này xong là ngủ ngon lành luôn đấy, đang định bảo bạn ý k hiểu chỗ nào thì hỏi chứ làm nguyên 1 bài như này thì khó
  0 · 5th April 2017 1:49
- Chee gee làm giàu không khó, à quên cực khó, nhưng dịch chiên ngành toán lý hóa... rất dễ vì từ vựng nó có 1 dúm ;) bạn nầy chắc mới bắt đầu hoặc giả chưa chịu làm giàu thoai!
  0 · 5th April 2017 1:55