Francis diagrams and Acetaldehyde?

[dRic2]

Hi,

my professor asked a friend of mine to draw the line for Acetaldehyde in the Francis diagrams. How can someone answer that question without knowing ##ΔG°(T)## of Acetaldehyde? Are there some qualitative consideration that can help me draw an approximated line ?

For example I thought that @T=1000-1200°C ##C_3CHO## should be less stable of ##CH_4## (right?) and it also should be less stable of benzene. Are my assumptions correct? And for other hydrocarbon ?

Thanks
Ric

 

[TeethWhitener]

I'm not sure how you would compare acetaldehyde with methane here. In the Francis diagrams I've seen, the compounds usually only contain carbon and hydrogen. With C, H, and O, you have to reference the heats of formation to the elements. So instead of comparing acetaldehyde and methane, you would have to compare acetaldehyde with methane + O₂ (or maybe methane + CO). I would think that, thermodynamically, acetaldehyde would be more stable than a mixture of methane and oxygen. But I'm just kind of guessing here, as I've never seen a Francis diagram with oxygen-containing compounds.

 

[dRic2]

I would think that, thermodynamically, acetaldehyde would be more stable than a mixture of methane and oxygen. But I'm just kind of guessing here, as I've never seen a Francis diagram with oxygen-containing compounds.

Me too, but this is as far as I can get. I can't think of anything more...