Question

Determine the enthalpy of formation for chlorine trifluoride, C1F3(g).
2C1F3(g) + 2NH3(g) --> N2(g) + 6HF(g) + Cl2(g) +1.200*10^3 KJ

Answer 1

Look up deltaHf^o, for each material, then
-1200 kJ = (n*dHfo produces) - (n*dHfo reactants)
Post your work if you get stuck.