[Juners]

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 Fe₃O_4(s) ------> 4 Al₂O_3(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 Fe₃O_4(s)?

[Borek]

It is limiting reagent question, nothing more complicated. 1 mole of Al reacting gives -3350/8 kJ.

[Juners]

Ohh, okay, makes sense..  

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?

[Borek]

I am assuming delta H given is for the reaction as written - thus if 8 moles of Al react, 3350kJ dissipates.