A culture of the fungus aspergillus niger is used industrially in the manufacture of citric acid and other organic species. Cells of the fungus have an ultimate analysis of CH1.79N0.2O0.5, and the heat of formation of this species is necessary to approximate the heat duty for the bioreactor in which citric acid is to be produced. You collect a dried sample of the fungus and determine its heat of combustion to be -550 kJ/ mol. Estimate the heat of formation ( kJ/ mol) of the dried fungus cells.