The ΔHrxn with the nearest tenth will have value of -60 K.
Explanation:
NF(g) + ___F2 (g) --> ___NF2 (g
data given:
½N2 (g) + ½F2 (g) -> NF (g) Hf = 86.6 kJ
½N2 (g) + F2 (g) -> NF2 (g) Hf = 33.8 kJ
Hess's law of heat is summation says that total change in enthalpy during a reaction is same whether the reaction is direct or in various steps.
½N2 (g) + ½F2 (g) -> NF (g) Hf = 86.6 kJ
reversing the equation we get:
NF -> ½N2 (g) + ½F2 (g)
Heat of enthalpy becomes negative so -86.6 KJ
Now adding both the reactions:
NF -> ½N2 (g) + ½F2 (g)
½N2 (g) + F2 (g) -> NF2 (g) Hf = 33.8 kJ
Removing the common entities from the reaction we get
F2 (g) + NF (g) --> ½F2 (g) + NF2 (g) Hf
the summation of enthalpy is
-86.6+ 33.8
= 52.8 KJ
The nearest tenth will be -60 KJ.
