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Author Topic: Thermite  (Read 62912 times)

Offline Xare

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Re: Thermite
« Reply #25 on: 21/09/2006 04:58:15 »

  Ok more on topic

 Did you know that when you add sulfer to thermite its called thermate.

 They add the sulfer because it helps lower the melting point of steel.

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Offline lightarrow

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Re: Thermite
« Reply #26 on: 21/09/2006 08:34:42 »
quote:
Originally posted by Xare

They add the sulfer because it helps lower the melting point of steel.
It's because FeS that lowers Fe melting point forming something like Fe2S?
 

Offline simpsonsman

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Re: Thermite
« Reply #27 on: 19/10/2006 21:11:26 »


1. me and my friends tried to make the rust for thermite by talking steel whoole and putting it in blench/ vinigar mix. Is this rust good enough.

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Offline Mr Andrew

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Re: Thermite
« Reply #28 on: 20/10/2006 02:19:55 »
If you just put it in water overnight it works just fine.

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Offline simpsonsman

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Re: Thermite
« Reply #29 on: 20/10/2006 03:22:56 »
so even thou we didnt use any water in the mix, we can still save it by putting it in water now?

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Offline lightarrow

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Re: Thermite
« Reply #30 on: 21/10/2006 14:39:05 »
quote:
Originally posted by simpsonsman

so even thou we didnt use any water in the mix, we can still save it by putting it in water now?
Rust is formed by the action of air oxygen on iron with the help of water.
 

Offline simpsonsman

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Re: Thermite
« Reply #31 on: 22/10/2006 02:58:38 »
I Know but to make the rust we didnt use any water. We stuck steel wool in blech/vinger mix. So can we make this rust usable by putting it in water?

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Offline lightarrow

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Re: Thermite
« Reply #32 on: 22/10/2006 11:11:32 »
quote:
Originally posted by simpsonsman

I Know but to make the rust we didnt use any water. We stuck steel wool in blech/vinger mix. So can we make this rust usable by putting it in water?
What I mean is that, if you have really made rust, certainly it won't become something else by putting it in water.

By "blech" you mean "bleach" I suppose. So, even if I have never made this reaction, I suppose FeCl3 (iron 3 chloride) is formed as well, and this is not exactly rust, and it's also hygroscopic. Have you already used this kind of rust for thermite?

Anyway, as Mr Andrew said, if you put iron whool in water, better if you add a little of oxygenated water and a little bit of acid (any, vinegar it's ok) and you let it react overnight, it's ok the same.

Then, you have to dry the rust powder in a kitchen burner (or similar), however, to convert any amount of Fe(OH)3 into FeOOH or Fe2O3.
« Last Edit: 22/10/2006 11:22:09 by lightarrow »
 

Offline simpsonsman

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Re: Thermite
« Reply #33 on: 23/10/2006 20:01:29 »
Well we have never used this rust before, i my friend thought that It wouldnt work becuase it was pure enough. So I just want to know can this rust be saved or should I just throw It out. And what do you mean by oxygenated water, Sorry i dont know much about chemestry

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Offline lightarrow

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Re: Thermite
« Reply #34 on: 24/10/2006 14:20:22 »
quote:
Originally posted by simpsonsman

Well we have never used this rust before, i my friend thought that It wouldnt work becuase it was pure enough. So I just want to know can this rust be saved or should I just throw It out. And what do you mean by oxygenated water, Sorry i dont know much about chemestry
Rust doesn't ruin with time. It just remains as it is, water or not water.
Oxygenated water is that solution we use as disinfectant: oxygen dissolved in water.
 

Offline simpsonsman

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Re: Thermite
« Reply #35 on: 24/10/2006 20:06:42 »
Im just asking, is rust usable for thermite?

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Offline lightarrow

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Re: Thermite
« Reply #36 on: 25/10/2006 15:29:03 »
Im just asking, is rust usable for thermite?
You mean that you asked if you can use rust for thermite after having put it in water?
If this is the question, the answer is No; as I have already written: you have to remove water from rust, to use it in the thermite.
 

Offline Mr Andrew

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Re: Thermite
« Reply #37 on: 02/11/2006 03:24:32 »
Simpsonsman, this is what i think the reaction of iron in bleach (sodium hypochlorite and sodium hydroxide) and vinegar would give:

12[H]+ + 6[OH]- + 6[ClO]- + 2Fe --> 2Fe(OH)3 + 3Cl2 + 6H2O

You wouldn't get much rust except what iron reacted with the water.  I could be wrong about this completely so don't take it as a truth without checking it with someone who knows more than me.
 

Offline lightarrow

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Re: Thermite
« Reply #38 on: 02/11/2006 08:16:19 »
I'm sorry Mr Andrew but I have to correct you. You can't write a chemical reaction where H+ and OH- ions are present at the same time, if bleach and vinegar (basic and acid respectively) have already mixed together. After mixing, the solution is either basic or acid, depending on the amount of vinegar you added. Tipically, adding an acid to bleach gives chlorine Cl2 (so, it's quite dangerous if you breath it!) wich is more oxidizing than bleach itself.
Then Cl2 reacts with Fe giving FeCl3 and so Fe3+ (iron chlorine is water soluble) which, in turn, reacts with water, if the solution is not acid, giving
Fe(OH)3: Fe3+ + 3H2O → Fe(OH)3 + 3H+.
 

Offline Mr Andrew

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Re: Thermite
« Reply #39 on: 02/11/2006 23:18:39 »
Wow, thank you lightarrow.  I should have caught that.  Yup, ferric chloride would form then.  That might run a thermite reaction but I wouldn't trust it to be entirely safe.  Anything with chlorine in it and very high temperatures should be regarded as dangerous (Cl2 gas is not pleasant to say the least).

I'm not positive about this but when iron reacts with oxygen in the presence of an water (or H+ ions more generally) Fe+3 ions form and O-2 ions combine with the H+ ions to make water.  This then reacts to form Fe2O3 or rust.  If Fe+3 ions could be made more quickly than by reacting iron directly with oxygen, in the presence of water, rust could be made to form more quickly.

As I understand it, H2O2 in the presence of protons is a very good oxidizing agent.  Would it be possible to put iron in a solution of peroxide and an acid like vinegar and get rust more quickly than in just plain old water?  If so, this would be better than leaving iron in water overnight because it would happen much more quickly.

The half reactions would look like this:

3(2e- + H2O2 + H+ --> 2H2O)
2(Fe --> Fe+3 + 3e-)
« Last Edit: 04/11/2006 20:08:15 by Mr Andrew »
 

Offline lightarrow

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Re: Thermite
« Reply #40 on: 03/11/2006 14:38:14 »
Everything correct. You have won a prize!
Remember however that every reaction involving iron in water solution is affected very much from the value of pH .
 

Offline Mr Andrew

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Re: Thermite
« Reply #41 on: 04/11/2006 20:05:43 »
Yay!!! ;D, What did I win?!? :P

When you said reactions of iron in water are affected by pH, am I right in saying that if the pH is too high, Fe(OH)3 would precipitate?  It shouldn't matter if it has a low pH, right...unless the conjugate base of the acid is insoluble when combined with Fe3+ ions.  But then again, if it was generally insoluble, it wouldn't be a strong acid and wouldn't lower the pH much.  I believe acetates are genereally soluble so it wouldn't really matter too much if vinegar was used.

So, simpsonsman, if you put roughly 1 part iron wool in a solution of 4 parts vinegar and 1 part peroxide (by mass, of course) you should get some rust fairly quickly.  This should be dried before use in a thermite reaction.  I must caution you about thermite: it creates temperatures hot enough to melt the iron produced and the aluminum powder needed is very dangerous.  I'm sorry to say, only a licensed chemist should try to run a thermite reaction because of the safety issues.
 

Offline simpsonsman

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Re: Thermite
« Reply #42 on: 07/11/2006 21:07:15 »
WOW, so you need iron wool for the rust, or will steel wool work?

 Is this rust i have useful or should i throw it out?

Can you make rust by burning steel wool with an electrical current?
 

Offline daveshorts

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Re: Thermite
« Reply #43 on: 08/11/2006 12:18:01 »
The only thing I would worry about if you were buring steel wool (apart from safety obviously) is that you are quite likely forming FeO rather than Fe2O3 - FeO tends to be black rather than brown. And this will have less oxygen to react with your aluminium.
 

Offline lightarrow

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Re: Thermite
« Reply #44 on: 08/11/2006 12:55:11 »
Yes. However is good the same for thermite. They say the best is Fe3O4. There isn't however a big difference from thermite made with FeO, Fe3O4, Fe2O3, providing that it's used the right stoichometry (I'm not sure this is the correct translation).
 

Offline lightarrow

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Re: Thermite
« Reply #45 on: 08/11/2006 13:13:34 »
Yay!!! ;D, What did I win?!?
You won a cool reputation!
Quote
When you said reactions of iron in water are affected by pH, am I right in saying that if the pH is too high, Fe(OH)3 would precipitate? It shouldn't matter if it has a low pH, right...unless the conjugate base of the acid is insoluble when combined with Fe3+ ions.
Ok.
Quote
But then again, if it was generally insoluble, it wouldn't be a strong acid and wouldn't lower the pH much.
For the special case of Fe3+ this is almost always true; in general it's not true: AgCl, for example, is insoluble, but HCl is a strong acid.
Quote
I believe acetates are genereally soluble so it wouldn't really matter too much if vinegar was used.
Yes, however acetic acid, or acetates in general, as organic substances can be oxidated by strong oxidizing agents, especially if these are in high concentration and with very low pH.
 

Offline simpsonsman

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Re: Thermite
« Reply #46 on: 03/12/2006 19:46:03 »
is it true that batery acid mixed with sugar makes a thermite like reaction?
 

Offline lightarrow

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Re: Thermite
« Reply #47 on: 05/12/2006 12:35:09 »
is it true that batery acid mixed with sugar makes a thermite like reaction?
"Thermite like" not at all. I know that concentrated sulfuric acid with sugar makes a vigorous exothermic reaction, which gives a black solid mass which grows quickly and comes out of the container, but I don't think diluted sulfuric acid (=battery acid) could give something of that kind. If you concentrate it, it's another story...
 

Offline moonfire

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Re: Thermite
« Reply #48 on: 05/12/2006 13:22:37 »
Whew!  that is a good thing..hehe...Hiya Alberto...miss you much...
 

Offline lightarrow

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Re: Thermite
« Reply #49 on: 05/12/2006 15:37:19 »
Hello Loretta! A kiss and a hug to you!
Have a good day!
P.S.
(I hope your comment on my previous post it's not what I think!)
« Last Edit: 05/12/2006 15:41:13 by lightarrow »
 

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Re: Thermite
« Reply #49 on: 05/12/2006 15:37:19 »

 

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