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Alpoism...?


Dorado

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Had a strange thought and couldn't come up with a solution.

Water does bad things to iron and steel. Causes or accelerates rusting. So here's where my question comes in. Water is H2O, rust is iron oxide or Fe2O3. If you were to have a pure iron bar and drop it into a sealed container of pure water. What would happen? Would it rust and release Hydrogen gas? Or would the purity of the water eliminate that possibility?

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IF the bar was pure iron with no impurities and IF the water was pure H2O then it would not corrode as the third side of the corrosion triangle (electrochemical potential) would be missing. However any impurities no matter how small in either the metal or the water would allow corrosion to happen

 

The Corrosion Triangles!

 

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Quote

Associated reactions

The rusting of iron is an electrochemical process that begins with the transfer of electrons from iron to oxygen.[5] The iron is the reducing agent (gives up electrons) while the oxygen is the oxidising agent (gains electrons). The rate of corrosion is affected by water and accelerated by electrolytes, as illustrated by the effects of road salt on the corrosion of automobiles. The key reaction is the reduction of oxygen:

O2 + 4 e + 2 H2O → 4 OH

Because it forms hydroxide ions, this process is strongly affected by the presence of acid. Indeed, the corrosion of most metals by oxygen is accelerated at low pH. Providing the electrons for the above reaction is the oxidation of iron that may be described as follows:

Fe → Fe2+ + 2 e

The following redox reaction also occurs in the presence of water and is crucial to the formation of rust:

4 Fe2+ + O2 → 4 Fe3+ + 2 O2−

In addition, the following multistep acid–base reactions affect the course of rust formation:

Fe2+ + 2  H2O ⇌ Fe(OH)2 + 2 H+
Fe3+ + 3  H2O ⇌ Fe(OH)3 + 3 H+

as do the following dehydration equilibria:

Fe(OH)2 ⇌ FeO + H2O
Fe(OH)3 ⇌ FeO(OH) + H2O
2 FeO(OH) ⇌ Fe2O3 + H2O

From the above equations, it is also seen that the corrosion products are dictated by the availability of water and oxygen. With limited dissolved oxygen, iron(II)-containing materials are favoured, including FeO and black lodestone or magnetite (Fe3O4). High oxygen concentrations favour ferric materials with the nominal formulae Fe(OH)3−xOx2. The nature of rust changes with time, reflecting the slow rates of the reactions of solids.

Furthermore, these complex processes are affected by the presence of other ions, such as Ca2+, which serve as electrolytes which accelerate rust formation, or combine with the hydroxides and oxides of iron to precipitate a variety of Ca, Fe, O, OH species.

Onset of rusting can also be detected in laboratory with the use of ferroxyl indicator solution. The solution detects both Fe2+ ions and hydroxyl ions. Formation of Fe2+ ions and hydroxyl ions are indicated by blue and pink patches respectively.

 

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I did not do well in chemistry. I was a Biology major before switching to Business. Never heard of the corrosion triangle.

 

 

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Easiest understanding, using periodic table. After Helium, elements like having 8 Electrons in their outer shell. They will borrow Electrons to keep and achieve that level. Water is made of Oxygen with 6 outer electrons, and 2 Hydrogen atoms that have 1 Electron each. By borrowing and sharing these electrons in a reduction reaction. FeO(OH)  the common surface rust we see is created on iron submerged in water, or water on iron.

The chemical reaction is called corrosion. If iron is left outside, exposed to oxygen and water, (rain, moisture, etc. ), The most common form of rust begins, Fe203.

Iron in Salt water will rust faster then fresh water. The salt acts as a catalyst, and accelerates the corrosion. Salt is an electrolyte, and adds Ions to the water. MT

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Marshal, if my teacher would have explained things the way you just did I may have learned a bit about chemistry and how the periodic tables worked...Well, better late than never.

Thank You! I just learned something today.:D

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19 minutes ago, Pat Riot, SASS #13748 said:

Marshal, if my teacher would have explained things the way you just did I may have learned a bit about chemistry and how the periodic tables worked...Well, better late than never.

Thank You! I just learned something today.:D

Don't forget about dissimilar Metal corrosion. or galvanic, or bimetallic corrosion. Something we had to closely watch in the chemical and refineries. Also chemical contacts with even copper piping on something as simple as Flow Meters, or control valves. MT

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Chemistry was a bust for me. Now things like Linear Momentum/Physics, let me at it. 

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6 minutes ago, Smoken D said:

Chemistry was a bust for me. Now things like Linear Momentum/Physics, let me at it. 

Your a better man to comprehend the mass, velocity etc. I always got lost on this.  MT

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I preferred math.  So much fun to wander around in the Matrices and Vector Spaces gathering Groups and Semigroups, forever searching a countably infinite number of sets of real and imaginary objects, analyzing bifurcation topological arborescences, seeking roots, investigating Primes, arguing whether or not P=nP ever.  

 

All very rational indeed, except, of course, when it was irrational.  And when it was irrational it was exponentially imaginary.

 

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2 hours ago, Allie Mo, SASS No. 25217 said:

For me substitute Geometry :( for Chemistry and Algebra :wub: for Linear Momentum/Physics. Otherwise I have no clue what you are talking about. :o;)

 

Now just wait a darn minute. You mean to tell us that we have to KNOW what we are talking about??? :o :D

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