Comment
Figure shows only the first and second heating processes. Both experimental conditions were different in the shape and the weight of reference materials. Sulfidation proceeds over 315-540Ž.
The enthalpy of reaction ĢHr=-926J/g.
The enthalpy of formation
@Product is the hexagonal WS2. Other impurity is nonreacted W as the residual. The reaction W + 2S= WS2 gives
the enthalpy of formation, ĢHf=54.6Kcal/mol.