Comment
Figure shows only the first and second heating processes.
Sulfidation reaction starts at 240�Ž, and finishes at 485�Ž.
ĢHr=839.5J/g.
The enthalpy of formation
�@Product is the hexagonal Ni(1-x)S. A little of cubic NiS2 is coexisted. If all products are NiS, the enthalpy of formation becomes ƒ¢Hf=18.2Kcal/mol.