Morgan
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Curious nature of rust
Some rust tidbits from the year 1906.
Why Iron Rusts
http://chestofbooks.com/crafts/popular-mechanics/Amateur-Wor...
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The WiZard is In
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Ding.
Rusty cannon balls —
Goodness gracious! Two British chemists believe they have solved
the 26-year-old mystery of how shipwrecked cannonballs that
were rescued from the deep spontaneously erupted into great balls
of fire.
"They were glowing bright red and you could feel the heat coming
off them as the desk began to smoke," recalls Bob Child, now a
chemist at the National Museums and Galleries of Wales in Cardiff."
http://boards.straightdope.com/sdmb/showthread.php?t=114195
NB - One dead link.
djh
----
In her particular nature, women
is defective and misbegotten,
for the active force in the male
seed tends to the production
of a perfect likeness in the
masculine sex; while the
production of woman is due
to a weakness in the generative
force or imperfection in the
preexisting matter or even from
some external influence, for
example, the humid winds from
the south.
St. Thomas Aquinas
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Morgan
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More rusty points to ponder.
http://io9.com/5651698/why-old-cannonballs-brought-up-from-t...
http://www.bigsiteofamazingfacts.com/why-do-old-cast-iron-ca...
http://www.nature.com/nrmicro/journal/v6/n6/full/nrmicro1892...
[Edited on 30-5-2011 by Morgan]
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LanthanumK
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Has the claim about carbon dioxide being necessary for iron corrosion been disproved?
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Morgan
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In the rust article he states pure water as a criteria too. Perhaps anything that would create a "galvanic" or ionic action would greatly accelerate
the process, just a few metal ions of some other metal in the water would be a catalyst to initiate a cascade of rust.Seems if you heated the iron red
hot in pure oxygen, it would "rust" very quickly, but that's not the experiment of course. Another factor might be the surface area, he doesn't say
what the shape or size or smoothness of the iron is in the experiment or the purity.
"But if the air were not freed from carbon dioxide rusting commenced at once, and in seventy-two hours the whole of the metal was corroded. There
would seem to be no basis, therefore, for the assumtion that iron can be caused to rust by pure water and pure oxygen only."
[Edited on 9-6-2011 by Morgan]
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Morgan
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I came across this today - just a few crumbs.
"When iron is in contact with water and oxygen, or other strong oxidants and/or acids, it rusts. If salt is present as, for example, in salt water, it
tends to rust more quickly, as a result of the electro-chemical reactions. Iron metal is relatively unaffected by pure water or by dry oxygen."
http://en.wikipedia.org/wiki/Rust
Another angle but pure water isn't a good electrolyte I don't think.
http://science.howstuffworks.com/question445.htm
"Rusting is the term specifically used to describe the corrosion of iron and steel. Water and air are needed before rusting will take place. The water
is a conducting medium and needs to contain some dissolved substances, however rainwater always contains some dissolved carbon dioxide which allows it
to act as an electrolyte. The presence of substances such as salt which makes water a better conducting medium will speed up the process of rusting."
http://www.jghs.edin.sch.uk/Departments/MathScience/chemistr...
[Edited on 10-6-2011 by Morgan]
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LanthanumK
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So it appears that without electrolytes, iron rusting occurs at a negligible rate.
hibernating...
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White Yeti
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Correct me if I am wrong:
Rusting is an autocatalytic process where iron atoms oxidize (release electrons). If WATER is present, the iron ions diffuse into the water and stay
there. Meanwhile, those aforementioned electrons, react with oxygen dissolved in the water to form OH- ions. This is why ungalvanized iron will rust
if left outside in the rain. If it is left outside in a desert, corrosion would take place much slower. You need both WATER and oxygen.
This is why the iron didn't corrode in a pure oxygen atmosphere.
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Morgan
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"Dr. G. T. Moody has shown that if very special pre-cautions are taken to exclude all traces of carbon dioxide, then iron may be left in contact with
pure oxygen and water for many weeks without undergoing any change. In one of the experiments thirty times as much oxygen as is required to convert
the whole of the iron into oxide was passed during the course of a few weeks, but there was absolutely no rust. But if the air were not freed from
carbon dioxide rusting commenced at once, and in seventy-two hours the whole of the metal was corroded. There would seem to be no basis, therefore,
for the assumtion that iron can be caused to rust by pure water and pure oxygen only."
Some rust tidbits from the year 1906. (First post)
Why Iron Rusts
http://chestofbooks.com/crafts/popular-mechanics/Amateur-Wor...
(6th Post)
"Rusting is the term specifically used to describe the corrosion of iron and steel. Water and air are needed before rusting will take place. The water
is a conducting medium and needs to contain some dissolved substances, however rainwater always contains some dissolved carbon dioxide which allows it
to act as an electrolyte. The presence of substances such as salt which makes water a better conducting medium will speed up the process of rusting."
http://www.jghs.edin.sch.uk/Departments/MathScience/chemistr...
[Edited on 30-7-2011 by Morgan]
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White Yeti
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What do you mean by pure water? Distilled or de-ionized?
It is no wonder the iron didn't rust in a pure oxygen atmosphere if de-ionized water was used.
Iron will rust when exposed to both oxygen and tapwater. Carbon dioxide may accelerate rusting, but so will dissolved ions and so forth.
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