Calc ΔH of Formation CO2 in Fe2O3 + 3C --> 4Fe + 3CO2 Reaction

[curtbranford]

Hi. It's my first time posting here. I did a quick search, but I couldn't find any existing threads addressing my question, so here it is:

Fe2O3 (s) + 3 C (gr) --> 4 Fe (s) + 3 CO2 (g)

What is the ΔH of formation of CO2 (g) at 298 K if the following is true of the above reaction at 298 K:

• Keq = 5.80 x 10-53
• ΔSorxn = 0.522 kJ/K
• ΔHoformation of Fe2O3 (s) = -795 kJ/mol

I know that the correct answer is -114 kJ/mol, but I can't figure out how to get there. Here's what I've done so far:

ΔGo = -RT lnK
=-298kJ

ΔGo = ΔHo -TΔSo
ΔHo = -298kJ + (298K)(.522kJ/K)
= -142.44 kJ

-142.44kJ = 3ΔH (CO2) - 795 kJ
3ΔH (CO2) = 652.5 kJ
ΔH (CO2) = 217.5 kJ

Which obviously isn't the right answer, but I don't see where I went wrong. Anybody see what I don't?

 

[GCT]

Hi. It's my first time posting here. I did a quick search, but I couldn't find any existing threads addressing my question, so here it is:

Fe2O3 (s) + 3 C (gr) --> 4 Fe (s) + 3 CO2 (g)

What is the ΔH of formation of CO2 (g) at 298 K if the following is true of the above reaction at 298 K:

• Keq = 5.80 x 10-53
• ΔSorxn = 0.522 kJ/K
• ΔHoformation of Fe2O3 (s) = -795 kJ/mol

I know that the correct answer is -114 kJ/mol, but I can't figure out how to get there. Here's what I've done so far:

ΔGo = -RT lnK
=-298kJ

ΔGo = ΔHo -TΔSo
ΔHo = -298kJ + (298K)(.522kJ/K)
= -142.44 kJ

-142.44kJ = 3ΔH (CO2) - 795 kJ
3ΔH (CO2) = 652.5 kJ
ΔH (CO2) = 217.5 kJ

Which obviously isn't the right answer, but I don't see where I went wrong. Anybody see what I don't?

The reaction is not balanced , and next your last portion of work is wrong.