Talk:Boudouard reaction
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Endo or exothermic reaction
[edit]Hi, I wanted to clarify whether it's an endothermic or exothermic reaction. In fact DeltaH is positive so for me it's an endothermic reaction because Enthalpy variation is positive. I've seen this elsewhere in my bibliography on Boudouard Reaction. Nicolas22031998 (talk) 09:08, 9 August 2023 (UTC)
- It is endothermic if you look at the conditions at STP, so after cooling things back down. If you look at the Gibbs energy you get:
- d_R_G = d_R_H - d_R_S * T
- Change in Gibbs energy = change in enthalpy minus change in entropy times absolute temperature
- And that is negative if you are above ~700 °C (energy is released). At that point CO is favored (exothermic), which is why there is >50 % CO for every temperature above this, assuming equilibrium.
- The same happens with things like diamond: The reaction to Graphite is favored at STP, but at high pressure and temperatures diamond is favored (more energetically stable, most exothermic, least endothermic). Eheran (talk) 10:08, 28 October 2024 (UTC)