Question on the reduction of FeO by CO

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In summary: So, the equilibrium CO2/CO ratio depends on the temperature.In summary, the author found standard enthalpy and entropy values for a reaction between Fe and CO at 298K. The reaction occurs at 1200K, but the equilibrium CO2/CO ratio is dependent on the temperature.
  • #1
hurreechunder
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Some numbers below: these are the standard molar enthalpies and entropies at 298K that I got from a website.
In the reaction FeO + CO = Fe + CO2, the deltas are:
delta H = (0+ -393) - (-266.5+ -110.5) = -16.3 KJ/mol.
delta S = (27.2+213.8) - (197.9+54) = -10.9 J/mol/K
Now at 1200 K,
Go = -16.3 + (1200)(-10.9) = -3.23
I have ignored the effect of temperature on enthalpy as both the reactants and the products are at the same temperature.
The issue with this is that it suggests that the reaction is spontaneous at 1200K. Therefore, in G = Go + RT ln Q, ln Q is >0 and therefore pCO2/pCO>1. However, we know the opposite to be the case in real life where pCO2/pCO = 1/2.3 in the blast furnace
Where am I going wrong??

Hf (KJ/mol K)Sf (J/mol K)
FeOs
-266.5​
54​
COg
-110.5​
197.9​
CO2g
-393.3​
213.8​
Fes
0​
27.2​
 
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  • #2
hurreechunder said:
I have ignored the effect of temperature on enthalpy as both the reactants and the products are at the same temperature.
hurreechunder said:
Where am I going wrong??
 
  • #3
Thanks - I took a second look at the calcs, and it appears that I was dividing the Cp in KJ/Kg by the molar mass instead of multiplying it. With that adjustment, the temperature adjustment of the enthalpy is no longer negligible. I am still getting a number different than 2.3, but at least Ln(Q) is negative.
 
  • #4
hurreechunder said:
Therefore, in G = Go + RT ln Q, ln Q is >0
What are you taking as G and G0 here?
Are you assuming that the blast furnace is at equilibrium? Is that true? Do they add extra CO to force the reaction to the right?
 
  • #5
dG (note: should have used the deltas in the original post) = 0 in the limiting case. I'm trying to find the corresponding value of ln Q = pCO2/pCO

dGo = dH-TdS; where for every reactant and product, H = Ho + Cp(T-298K). It's a bit complicated because the Cp itself changes with temperature.

The blast furnace has many zones in it, corresponding to different temperatures, as the iron ore travels down from the top and the CO comes up from the bottom. The CO is not injected externally. The ratio of CO2 to CO comes about from thermodynamic balance as the CO travels up from the bottom and reduces the iron ore in the layers above.
 

1. What is the reaction for the reduction of FeO by CO?

The reaction for the reduction of FeO by CO is FeO + CO → Fe + CO2.

2. What is the purpose of reducing FeO by CO?

The purpose of reducing FeO by CO is to convert iron oxide (FeO) into elemental iron (Fe) by removing oxygen from the compound.

3. What are the conditions required for the reduction of FeO by CO?

The reduction of FeO by CO typically occurs at high temperatures (between 800-1200°C) and in the presence of a reducing agent, such as carbon monoxide (CO).

4. What are the potential applications of the reduction of FeO by CO?

The reduction of FeO by CO is commonly used in the production of iron and steel. It can also be used in the production of other iron-based alloys and in the purification of iron ores.

5. What are the potential risks associated with the reduction of FeO by CO?

The reduction of FeO by CO can produce carbon monoxide gas, which is toxic and can be harmful if inhaled in large quantities. Therefore, proper safety measures, such as ventilation and protective equipment, should be taken when conducting this reaction.

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