Heat of Formation
posted by Kyle .
When 10.00 g of iron is burned in O2(g)to form Fe3O4 (s) , enough heat is generated to raise the temperature of 784 g of water from 18.0 C to 38.0 C.
Calculate the heat of formation of Fe3O4 (s) under these conditions in kJ/mol.

Assume you have one mole of FeO.Fe2O3
Find the mol mass of that.
Then find how many moles you have in 10g
heatformation= masswater*specificheat*20C/molesFeO.Fe2O3 
I got 1518 kJ/mol using that equation, but I still got it wrong. Did I do something wrong?

Let me see your data.
molesIronoxide= ...
specific heat constant.... 
0.04319 moles F3O4
Specific Heat Constant: 4.18 J/mol*C