How to find the molar enthapy of Ammonium nitrate?

Answer 1

Write the equation for formation of NH₄NO₃ from elements in standard form.

N₂(g) + 2H₂(g) + 3/2 O₂(g) ==> NH₄NO₃(s)

You then need to find equations with known ∆H values so you can use them and Hess' Law. For example:

1/2N₂(g) + 3/2 H₂(g) ==> NH₃

1/2 H₂(g) + 1/2N₂(g) + 3/2O₂(g) ==> HNO₃

add these together to get the desired reaction:

N₂(g) + 2H₂(g) + 3/2O₂(g) ==> NH₃ + HNO₃ and...

NH₃ + HNO₃ ==> NH₄NO₃