Not logged in [Login ]
 Sciencemadness Discussion Board » Fundamentals » Chemistry in General » Really need help on this! Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Beginnings   » Responsible Practices   » Miscellaneous Engineering and Equipment   » Reagents and Apparatus Acquisition   » Electronics   » Process Engineering   » Materials and Metallurgy Special Topics   » Analytical Chemistry   » Electrochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques Literature and Documentation   » Sciencemadness Wiki   » Prepublication Non-science   » Forum Matters   » Legal and Societal Issues

Author: Subject: Really need help on this!
Derge
Harmless

Posts: 7
Registered: 29-6-2008
Member Is Offline

Mood: No Mood

Really need help on this!

I've been a 'lurker' for a while here but finally realized I should join since I now have a decent question.

First is this following equation of mine correct regarding thermite?

2Al + Fe2O3 = Al2O3 + 2Fe
One mole of Al weighs 27 g. 0.5 mole of Fe2O3 weighs 80 g.
Therefore, (27 + 80) g = 107 g of Al and Fe2O3 is needed to produce 54 g of Fe.
That means the mass of the reactants to that of Fe produced is a ratio of 107/54 = 2. The mass of thermite reactants (Al, Fe2O3) is twice that of the molten iron produced.

I am trying to find out the amound of material is needed if I have say, 5909 grams of Fe.

It's regarding me trying to disprove some wacko about the 9/11 attacks.

Thank you all!
12AX7
Post Harlot

Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline

Mood: informative

There are plenty of thermite resources at your disposal, I think you will find the necessary information quite readily. That leaves discussion for other questions, like why you're bothering to "disprove some wacko", which sounds like a fruitless endeavor.

Tim

Seven Transistor Labs LLC http://seventransistorlabs.com/
Electronic Design, from Concept to Layout.
Need engineering assistance? Drop me a message!
Derge
Harmless

Posts: 7
Registered: 29-6-2008
Member Is Offline

Mood: No Mood

Well, that's quite helpful. I appreciate your (obvious) assistance. And no, they are not readily available. Or else I would not be here, now would I?
DJF90
International Hazard

Posts: 2266
Registered: 15-12-2007
Location: At the bench
Member Is Offline

Mood: No Mood

1 mole of Fe weighs 56g, so according to your equation, [(2x27)+(2x56)+(3x16)= 214] grams of reactants yeilds 112g of Fe. so for 5909g of Fe to be produced, [(5909/112)x214] grams of reactants are needed (if i'm not mistaken).
not_important
International Hazard

Posts: 3873
Registered: 21-7-2006
Member Is Offline

Mood: No Mood

Your question isa one of rather simple arithmetic, the way you phrased it.

However, for what you seem to be saying you're trying to do, the question is not correct. The products from a thermite reaction are hot enough to melt additional iron/steel, so simple stoichiometry of the reaction is not enough. You'll need to know the temperature of the products, how much heat was lost, calculate how much heat is conducted away from the structural steel so you can figure how much of it could have been melted by the assumed thermite mass.

Then there's the question if the updraft in the elevator shafts combined with the melted plastics and combustible fumes sucked into the shafts could create a high enough temperature to melt steel, especially if the updraft blast flame runs rich and contains carbon that could dissolve in the steel.
Derge
Harmless

Posts: 7
Registered: 29-6-2008
Member Is Offline

Mood: No Mood

not_important: Thank you for the contribution! I slightly undertstood the question but I wasn't sure if the equation I attempted was correct (going off absolute zero knowledge of chemistry). The thermodynamics is basically all to be assumed, I wouldn't have an ability to determine heat loss/gain. I may try some more research into that!

DJF90: Is there some calculations to determine the mole of any units? (I think I'll read up on it)

Thank both! Some of the stuff y'all talk about on this forumn is really pushing me to learn chemisty, and I have a love affair with physics, so I guess it should come naturally.

The best thread was the hydrofluoric acids. Wicked evil stuff.
I may even start being able to weigh in on some things!
DJF90
International Hazard

Posts: 2266
Registered: 15-12-2007
Location: At the bench
Member Is Offline

Mood: No Mood

Calculations to determine the mole of any units? Can you please rephrase this? The only thing that I think you are after is this:

moles = (mass of substance)/(relative molecular mass of the substance)

One mole is 6.02 x10^23 atoms of the substance (this number is called Avogadro's number)

To work out the number of moles of a substance in a volume of solution of known concentration:
moles = concentration of the solution (measured in moles per litre (moldm^-3)) x volume of solution (measured in litres - 1cm^3 = 0.001 dm^3).

I hope this provides you with the basics for moles calculations. Once you know some basic chemistry a good site to learn from is http://www.chemguide.co.uk/ , although you need some background knowledge of the subject to make it useable.

For this "background information" I suggest the use of this link - http://www.s-cool.co.uk/topic_index.asp?subject_id=21 ; It covers the basics that you will need before you can further your knowledge

[Edited on 29-6-2008 by DJF90]
12AX7
Post Harlot

Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline

Mood: informative

 Quote: Originally posted by Derge Well, that's quite helpful. I appreciate your (obvious) assistance. And no, they are not readily available. Or else I would not be here, now would I?

I'm not so sure about that; I've seen many newbies ask for surprisingly obvious things. I'm obliged to spoonfeed them as little as possible for starters.

I find the ratio of 3:1 (by weight) on the ~5th hit down on Google "thermite ratio" (no quotes):
http://www.amazingrust.com/Experiments/how_to/Thermite.html
A few pages down are the proportions, plus all kinds of richness as far as chemistry you might want to know.

Tim

[Edited on 6-29-2008 by 12AX7]

Seven Transistor Labs LLC http://seventransistorlabs.com/
Electronic Design, from Concept to Layout.
Need engineering assistance? Drop me a message!
mac251
Harmless

Posts: 2
Registered: 30-6-2008
Location: Texas
Member Is Offline

Mood: OK

People can also find this info. on a lot more sites. Heck its even listed on Wikipedia. They give military grade ratio and commercial grade ratio.
blogfast25
International Hazard

Posts: 10562
Registered: 3-2-2008
Location: Neverland
Member Is Offline

Mood: No Mood

 Quote: [quote It's regarding me trying to disprove some wacko about the 9/11 attacks. Thank you all!

Without defining the exact assumptions your wacko is trying to defend (re. 9/11) it'll be very difficult to actually come up with something that is a decent rebuttal of his position.

One (and only one) of the reasons why the conspiracy theorists feel comfortable with the 'controlled demolitions by thermite charges' theorette is that iron oxide based thermites do indeed have the potential to melt steel in a jiffy but that doesn't mean anything at all. In essence the issue becomes a complex engineering problem where a multitude of factors have to be taken into account, including the end-temperature reached by the reacting thermite mixture, heat losses during the burn and mass and thickness of any steel object one would like to weaken/damage/destroy/burn right through (etc etc), load of the bearing steel, to name but a few.

On the end-temperature reached by a burning thermite mixture alone, one can pontificate rather lengthily, as this factor in itself depends largely on several factors such as granulometry of ingredients and whether or not the generated heat is being contained as much as possible or allowed to leak away.

For ferric oxide (Fe<sub>2</sub>O<sub>3</sub>, the amount of heat generated (@ 298 K) is a rocking 851.50 kJ per mol of reacted oxide (to put this into perspective, it's enough heat to raise the temperature of 2 kg of iced water to its boiling point). From the heat capacities and heats of fusion of the reaction products (Fe and alumina) the end-temperature in adiabatic (no heat exchange with the surrounding environment) conditions can be worked out using the method described in this post.

There is little doubt that various thermite mixtures (and not just ferric thermite) can easily (but still depending on conditions) reach the melting point of the highest melting steels and backyard enthusiasts (like me) routinely reach such temperatures with homebrewed mixes.

If the hot thermite mass charge is large enough vis a vis the target object's mass it would be possible to destroy almost anything with melting points up to 2,500 to 3,000 C (4,500 F to 5,400 F). So it's impossible to win the argument on thermochemical grounds: cleverly engineered thermite charges could indeed destroy just about any load bearing metal structure.

But the idea that Government agents put in place such charges, prior or during the attacks to cause the destruction of the towers, strikes me as preposterous. And the onus to prove that they did lays with the conspiracy nutjobs...

I hope my comment doesn't set off a frenzy of conspiracy discussions here: there are plenty wacky forums whose only raison d'ĂȘtre is just that.

[Edited on 30-6-2008 by blogfast25]
Derge
Harmless

Posts: 7
Registered: 29-6-2008
Member Is Offline

Mood: No Mood

 Quote: Originally posted by mac251 People can also find this info. on a lot more sites. Heck its even listed on Wikipedia. They give military grade ratio and commercial grade ratio.

Wikipedia... that's a joke right
Derge
Harmless

Posts: 7
Registered: 29-6-2008
Member Is Offline

Mood: No Mood

 Quote: Originally posted by DJF90moles = (mass of substance)/(relative molecular mass of the substance) I hope this provides you with the basics for moles calculations. Once you know some basic chemistry a good site to learn from is http://www.chemguide.co.uk/ , although you need some background knowledge of the subject to make it useable. For this "background information" I suggest the use of this link - http://www.s-cool.co.uk/topic_index.asp?subject_id=21 ; It covers the basics that you will need before you can further your knowledge [Edited on 29-6-2008 by DJF90]
That's very beneficial, thank you!
Derge
Harmless

Posts: 7
Registered: 29-6-2008
Member Is Offline

Mood: No Mood

 Quote: Originally posted by blogfast25 Without defining the exact assumptions your wacko is trying to defend (re. 9/11) it'll be very difficult to actually come up with something that is a decent rebuttal of his position.
I've studied extensively on the structural engineering of the Towers. Basically with the help here I've shown that generic thermite would require 5664 pounds for all perimeter columns on one floor under ideals conditions that both you and not_important have explained we don't know.
 Quote: Originally posted by blogfast25For ferric oxide (Fe2O3, the amount of heat generated (@ 298 K) is a rocking 851.50 kJ per mol of reacted oxide
Jesus L Crisco.
 Quote: Originally posted by blogfast25 But the idea that Government agents put in place such charges, prior or during the attacks to cause the destruction of the towers, strikes me as preposterous. And the onus to prove that they did lays with the conspiracy nutjobs...
I needed most the basic, simple way to show the impossibilty to use that stuff.
 Quote: Originally posted by blogfast25 I hope my comment doesn't set off a frenzy of conspiracy discussions here: there are plenty wacky forums whose only raison d'ĂȘtre is just that. [Edited on 30-6-2008 by blogfast25]
I frequent the randi.org forumns where the the CT's are prevalent. I have a hobby debunking conspiracys of their 'grand delusion'. Kinda fun.
Derge
Harmless

Posts: 7
Registered: 29-6-2008
Member Is Offline

Mood: No Mood

 Quote: Originally posted by 12AX7 I'm not so sure about that; I've seen many newbies ask for surprisingly obvious things. I'm obliged to spoonfeed them as little as possible for starters.
I understand, but you got to get a foot somewhere
 Quote: Originally posted by 12AX7 I find the ratio of 3:1 (by weight) on the ~5th hit down on Google "thermite ratio" (no quotes): http://www.amazingrust.com/Experiments/how_to/Thermite.html A few pages down are the proportions, plus all kinds of richness as far as chemistry you might want to know. Tim [Edited on 6-29-2008 by 12AX7]
I so despise Googleing anything, for every 1 good info site you are swamped with 7 bad ones.

 Sciencemadness Discussion Board » Fundamentals » Chemistry in General » Really need help on this! Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Beginnings   » Responsible Practices   » Miscellaneous Engineering and Equipment   » Reagents and Apparatus Acquisition   » Electronics   » Process Engineering   » Materials and Metallurgy Special Topics   » Analytical Chemistry   » Electrochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques Literature and Documentation   » Sciencemadness Wiki   » Prepublication Non-science   » Forum Matters   » Legal and Societal Issues