How many kilocalories are involved in the production of 33.68 g of NH3?

I believe that the balanced chemical equation is:

3H2 (g) + N2 (g) →2NH3 (g), ΔH = - 21.9 kcal

We can see that 21.9 kcal of heat is released for every 2 moles of NH3.

The molar mass of NH3 is 17 g/mol, hence:

moles NH3 = 33.68 g / (17 g/mol)

moles NH3 = 1.98 mol

The total energy released is:

total heat = (-21.9 kcal / 2 mol) * 1.98 mol

total heat = - 21.70 kcal