[Needaask]

Why do we use electrolysis for the top most metal oxides and reduction with carbon for the moderately reactive metal oxides? Since using carbon is cheaper as the energy produced is more cost efficient why don't we just use more carbon for those more reactive metal oxides?

[Arkcon]

The answer is already in your question.  Or it should be, anyway.  You say we use carbon for moderately reactive metals, and hydrogen for "top most metal oxides."  Can you give us some examples, of the moderate and "top most" metal oxides?  And maybe a better term for "top most".

[Needaask]

The answer is already in your question.  Or it should be, anyway.  You say we use carbon for moderately reactive metals, and hydrogen for "top most metal oxides."  Can you give us some examples, of the moderate and "top most" metal oxides?  And maybe a better term for "top most".

HI

Sorry about that. I meant to say the metals at the top of the reactivity series like potassium oxide and for the moderately reactive metals, something like zinc oxide? If we use electrolysis for ZnO the reaction would be ZnO->Zn+O2 and if we use carbon the reaction would be ZnO+C->Zn+CO so roughly about the same energy is absorbed in the reaction. But still using carbon is cheaper than electrolysis. So i was thinking in KO more energy would be used up in the electrolysis as K+ is very reactive. So if we apply the same principles shouldn't it be better to have KO+C->K+CO even if now we have to supply more energy for the activation energy in the blast furnace but still as a whole it would be more cost effective to use carbon here.

Also from the other question I posted this: Hmm I was thinking if K2O+C->K+CO if we apply Hess's law K2O(s)->2K+(g)+O2-(g), C(s)->C(g) then O2-(g)+C(g)->CO(g)+2e, 2K+(g)+2e->2K(g) and K(g)->(s). So I don't really see why carbon is exclusively used for zinc oxides to copper (II) oxide.

Thanks so much for the help

[Arkcon]

Briefly, energy is not the reason a reduction (or any other chemical reaction) will or will not happen.

[Needaask]

Oh actually what's the reason why the reaction won't take place? Because in my textbook the only explanation they gave was that the bonds in the more reactive metal oxides like K2O or Na2O are too strong. So I always thought if i supplied more energy then the reaction would go on and furthermore, be more cost effective..

Thanks for the great insight though I always thought that energy was a big part of reactions.

[Borek]

I always thought that energy was a big part of reactions.

It is, but it is not the only thing to consider.

[Needaask]

I always thought that energy was a big part of reactions.

It is, but it is not the only thing to consider.

Hi Borek

Actually I posted this on another thread but I'm not sure if i should post it here because it applies too.

Like for  K2O(s)->2K+(g) +O2-(g),  C(s)->C(g) energy is absorbed and in O2-(g)+C(g)->CO(g)+2e, 2K+(g)+2e->2K(g) and  K(g)->K(s) energy is being released?


And for my O2-(g)+C(g)->CO(g)+2e it should be simplified to O2-(g)->O+2e and C+O->CO

I'm thinking this step by step process should be split into the bond breaking part of the reaction (which adds up to activation energy) and the bond forming part of the reaction (which adds up to the reverse activation energy).

So I would guess that energy is being put in to the bond breaking components of the reaction like this: http://postimg.org/image/6ufkwqa9d/

That's why I don't see why I can't use carbon for these reactions. Didn't carbon only increase the activation energy (cos i have to turn it into a gas) and also give out some energy (when it reformed CO). So thinking about this now if i were to just decompose 2K2O->4K+O2, then my activation energy would be smaller as now bond breaking or activation energy would just be: 2K2O(s)->4K+(g)+2O2-(g), 2O2-(g)->2O(g)+4e and bond forming would be: 4K+(g)+4e->4K(g), 4K(g)->4K(s) and 2O(g)->O2(g). So in this reaction won't the activation energy be smaller?

Hmm this is pretty confusing now.. I don't see the need for carbon besides it giving out energy with a reaction with an oxygen atom. Could you explain my misconceptions here? Thanks