I need some help to found the mistake in my reasoning :
I understand that the reaction carbon to diamon is endothermic. But, if i look the phase diagram of crabon the slope of the equilibrium curve for this transformation is positive. So dP/dT > 0. Clapeyron :
Moreover Vdiamon < Vgraphite so to have a positive slope we need have Delta H transition negative, this is caracteristic of exothermic reaction, no ?
Where is the mistake on my reasoning ?