Use Hess's Law or the summation equation to calculate the ΔHrxn. Round to the nearest tenth!! ___NF(g) + ___F2 (g) --> ___NF2 (g) ½N2 (g) + ½F2 (g) -> NF (g) Hf = 86.6 kJ ½N2 (g) + F2 (g) -> NF2 (g) Hf = 33.8 kJ

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)

there all right good

explanation:

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.