Answer:
ΔHrxn = -60 kJ ( to the nearest tenth)
Explanation:
The balanced chemical reaction for the equation is given as;
N2(g) + 3 F2(g) --> 2 NF3(g)
The individual steps are;
½N2 (g) + ½F2 (g) -> NF (g) Hf = 86.6 kJ
Turning the reaction above around (the energy sign would also change), we have;
NF (g) --> ½N2 (g) + ½F2 (g) Hf = - 86.6 kJ
½N2 (g) + F2 (g) -> NF2 (g) Hf = 33.8 kJ
Adding both reactions above and canceling the common entities, we have;
½N2 (g) + F2 (g) + NF (g) --> ½N2 (g) + ½F2 (g) + NF2 (g) Hf = -52.8 kJ
Taking out the common compound in both sides of the reaction, we have;
F2 (g) + NF (g) --> ½F2 (g) + NF2 (g) Hf = -52.8 kJ
ΔHrxn = - 52.8 kJ
ΔHrxn = -60 kJ ( to the nearest tenth)
