Calculate the amount of heat that's released when 45 grams of nitrogen reacts to form NH3?

The reaction between N₂ and H₂ to form NH₃ is exothermic (i.e. heat is released).
N₂ + 3H₂ → 2NH₃ ...... ΔH = -92.4 kJ•mol⁻¹

Molar mass of N₂ = 14.01 × 2 g•mol⁻¹ = 28.02 g•mol⁻¹
No. of moles of N₂ reacted = (45 g) / (28.02 g•mol⁻¹) = 1.61 mol

According to the equation, the reaction of 1 mole of N₂ releases 92.4 kJ of heat.
Heat released in the reaction = (92.4 kJ•mol⁻¹) × (1.61 mol) = 149 kJ

You need to check your reaction..
nitrogen reacts with hydrogen to give NH3 in an endothermic reaction. heat is absorbed not given out