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Topic: Thermite Reaction  (Read 5220 times)

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Juners

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Thermite Reaction
« on: December 03, 2005, 01:58:06 AM »
I have been sitting and staring at this question for about an hour, and I have no idea how to approach it. I've tried using specific heats, enthalpy characteristics, and I just cant get it. It's like I know what I'm doing, and cannot apply it in this situation.

The following thermite reaction is a major source of heat for welding:

8 Al(s) + 3 Fe3O4(s) ------> 4 Al2O3(s) + 9 Fe(s)

Delta H= -3350 kJ

How much heat is released in kJ by the reaction of 27.6g Al with 69.12g Fe3O4(s)?

Offline Borek

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Re:Thermite Reaction
« Reply #1 on: December 03, 2005, 04:32:29 AM »
It is limiting reagent question, nothing more complicated. 1 mole of Al reacting gives -3350/8 kJ.
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Juners

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Re:Thermite Reaction
« Reply #2 on: December 03, 2005, 01:06:27 PM »
Ohh, okay, makes sense..  :D

I understand now how it is limiting, however what I do not understand is what the -3350/8 kJ. Obviously the 8 would come from the coefficient on the Aluminum in the reactants, however what is the connection with the delta H?

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Re:Thermite Reaction
« Reply #3 on: December 03, 2005, 03:04:13 PM »
I am assuming delta H given is for the reaction as written - thus if 8 moles of Al react, 3350kJ dissipates.
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