1N2(g) reacts with H2(g) to form NH3(g), gaseous ammonia.

Question

Show balanced thermochemical equations based on both one mole and two moles of NH3(g).
Determine Ho ( for both reactions using Table 6.2 (Hof).
Use the summation equations.
Show your calculations
N2 +H2 NH3 when I looked up the standard enthalpies of formation at 25 degrees the numbers came out to be 0. I don't know how to even set this up. Do I balance the equation?

Answer 1

Of course I don't know the contents of Table 6.2.
For 2 mols NH3 the equation is
N2 + 3H2 ==> 2NH3 (for 2 mols) dH = -46.11*2 kJ
1/2 N2 + 3/2 H2 ==> NH3 (for 1 mol) dH = -46.11 kJ
You should add (g) to each to show the phase.
I don't know how you got 0. My tables show dHof for NH3 = -46.11 kJ/mol and of course zero for H2 and N2.
I don't know what summation equations are looking at.