5 days prior to the annual inspection cycle of your nuclear power plant, an iron

Question

5 days prior to the annual inspection cycle of your nuclear power plant, an iron pipe transporting 1M NaOH solution at 500°C to a storage tank ruptured.

Hearing of the failure, the chief chemist in your team runs in and states "this shouldn't have happened! The hematite should have protected the inside of the pipe! We inject 10^-10 molar (FeO4)^-2 into the system for a reason!" (FeO4^-2-->Fe2O3, Balance equation find the reduction potential and plug everything into the Nernst equation.)

You decide to do a walk-down along the section upstream of the pipe, and you notice 2 things:
1) the O2 inlet valve has been closed off, and
2) an in-line O2 detector shows 10^-26 atm O2.
(Use Ellingham diagrams)

You make a note of this value, then return to your window-less cubicle to write up the report.

What happened? What should the inlet valve have been set at? As the new-hire corrosion engineer, explain and justify your findings in a way that your supervisor would understand. Use Ellingham diagrams and the Nernst equation if necessary.

Explanation / Answer

From Ellingham diagram, vapor pressure value should be near 1 atm.
Hematite gets deposited non - uniformly at certain places and gets accumlated. This can be one probable reason
for damage on the pipe.

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