Comment@Figure shows DSC curves in the first and second heating processes. Sulfidation reaction occurs at 250-450Ž. There are two stages of reactions: first stage, peak at 275Ž,@second stage, peak, at 390Ž. Formation reaction of FeS has completely finished during first run, so that second run can be regarded as the blank curve in the system selected.
The enthalpy of formation@Final product is hexagonal
FeS. However, the product just after first stage of reaction is not crystalline but amorpous FeS. Calculated ĢHf=18.8Kcal/mol.
