Answer:
-1140 kJ/mol.
Explanation:
Let's consider the following balanced equation:
N₂O₄(l) + 2 N₂H₄(l) ⇒ 3 N₂(g) + 4 H₂O(g)
When 10.0 g of N₂O₄ react 124 kJ of heat are released. By convention, when heat is released we use the negative sign. Since the molar mass of N₂O₄ is 92.0 g/mol, the enthalpy of reaction is:
[tex]\Delta H=\frac{-124kJ}{10.0gN_{2}O_{4}} .\frac{92.0gN_{2}O_{4}}{1molN_{2}O_{4}} =-1140kJ/molN_{2}O_{4}[/tex]
