Comment
Figure shows first heating and cooling cycle.
Reaction occurs at 270�� (onset) and 275��(peak) with -305.7J/g, followed by the melting of product, 40.76J/g. In the cooling process: one peak at 268�� with -58.40J/g. �@
The enthalpy of formation
XRD and Ref. phase diagram
If the all heat content measured over 153-300�� comes from AsS formation, ��H becomes 32.7KJ/mol. This corresponds to about 7.8Kcal/mol