Naked Science Forum
General Science => General Science => Topic started by: ukmicky on 07/07/2008 22:02:31
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One of the best rust removers is vinegar it will remove the rust and leave gleaming metal behind but why is vinegar such a good rust removing product ,what chemical process does it use to remove it
Example
http://www.cookhaus.co.uk/vinegar/index.htm
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Weak acids can dissolve and loosen the crumbly hydrated iron oxide (which is what rust is) to form a soluble salt they can also replace it with a thin film of smooth hard oxide on the surface of the iron to help it resist further hydrated oxidation. Phosphoric acid (coca cola) , and citric acid (lemon juice) are other acidic rust removers.
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One of the best rust removers is vinegar it will remove the rust and leave gleaming metal behind but why is vinegar such a good rust removing product ,what chemical process does it use to remove it
Example
http://www.cookhaus.co.uk/vinegar/index.htm
Vinegar contains acetic acid CH3COOH which reacts with rust FeOOH:
3CH3COOH + FeOOH --> Fe(CH3COO)3 + 2H2O
and iron (III) acetate Fe(CH3COO)3 is water soluble.
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I love this method with old rusty tools me kids and hubby have left in the yard for a year with extreme rust a good soak and voila! Yayyyyyyyyy!.. Thanks for the answers guys and the Question Michael!.. Its always been my favorite way to remove rust!
Why does the vinegar turn the rust that floats to the surface Black and it gets smeary ... almost grease like when trying to wash it off from the tool and the hand... what causes that?
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If what you're trying to clean is too big to immerse in vinegar, try using ketchup.
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You mean spread it on??? I have seen ketchup take on that same acidic black gunk when spilled on things!
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Yup - spread it on [;D]
In addition to vinegar, I think it also contains some other fruit based acids, so works in the same way.
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Yup - spread it on [;D]
In addition to vinegar, I think it also contains some other fruit based acids, so works in the same way.
If then you add mayonnaise, it's even better [;D] [;D]
(it contains citric acid and vinegar)
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Heh - never tried mayonnaise. I guess salad cream would work too.
Ketchup is also good for cleaning the bottoms of burnt saucepans, especially those copper-bottomed ones - I learned that from my parents who noticed it by chance - one of them accidentally spilled some ketchup on a stained saucepan which had been washed and was draining dry but they didn't wipe it off until they'd finished eating...
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Does this mean that a frozen crinkled (soaked in vinegar) chip will make a good scouring brush and boot cleaner ?
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Hee hee hee?
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Yup - spread it on [;D]
In addition to vinegar, I think it also contains some other fruit based acids, so works in the same way.
Yes I should have thought.. I know how acidy Ketchup is because of the tomatoes but the ketchup I forgot contains vinegar also...! LOL...
The goat should be happy eh.. ketchup mayonnaise and a nice copper pot! LOL Bon-appetite!
If then you add mayonnaise, it's even better [;D] [;D]
(it contains citric acid and vinegar)
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I realize this thread is incredibly ancient, but it has information I'm looking for. I only have one small question: I am wanting to remove rust from a very large object. So instead of buying 30 gallons of vinegar, I thought I could just take water and bring the pH down to a acidic level similar to vinegar. I was able to do this with sulfuric acid normally used in an industrial situation. So despite the water being acidic, not much seems to be happening. why?
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What concentration of sulphuric acid are you using?
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I believe it is 70-80% Extremely powerful stuff, at any rate....
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Are you treating the rust with 70% acid?
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It seems I did not explain myself very well. I used the 70% acid to bring the pH level of the water down to around 2. This is a pH level similar to vinegar, yet no significant derusting has taken place and I am wondering why.
I realize that it can sometimes be hard to deal with members new to a particular forum and I apologize if I am being an inconvenience in any way.
Thanks for your help.
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If you have a solution of a strong acid that's pH2 it's pretty dilute; about 0.1%
You need much more of a weak acid like acetic acid to get that pH. Vinegar is typically 5%
There's just not enough stuff there to do the job.
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Sir, I see exactly what you are saying. It seems fairly obvious to me now that I think about it. Thanks again for taking the time to answer my question.
Blessings,
Anthony W.
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I realize that it can sometimes be hard to deal with members new to a particular forum and I apologize if I am being an inconvenience in any way.
Thanks for your help.
Tony, you will have received a welcome message from me, but I'll say a welcome here as well.
Yours is the sort of question we like to see asked and to be able to answer so no need to apologise.
I might ask Bored Chemist if he could confirm the post #2 is also a rust removing mechanism.
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There are a few things in post 2 that could be "rust removing"
Acids will dissolve metal oxides to form salts- if those salts are soluble you get rid of the rust.
If they form an insoluble salt- phosphoric acid is the commonest example, you get a different outcome. You don't get to the metal, but you get a layer of iron phosphates which can act as a "rust proofing" coating.
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I know this is an old, thread but I have also been trying very hard to find the answer to the original question, which no one has yet answered "Why does the vinegar turn the rust that floats to the surface Black and it gets smeary ... almost grease like when trying to wash it off from the tool and the hand... what causes that?"
Can someone please answer this?
thanks