Ammonium Nitrate (80 $\Delta$ E )Of the Reaction System? (1 L $\to$

Ammonium nitrate (80.04 g/mol)decomposes at high temperatures to form nitrogen,oxygen,and water vapor.Suppose 750 grams decomposes at 350°C and 0.98 atm,generating gases that expand by about 960 L.How much P-V work is done? What is the approximate change in internal energy ( $\Delta$ E )of the reaction system? (1 L . atm = 101.3 J)
NH₄NO₃(s) $\to$ N₂(g)+ O₂(g)+ H₂O(g) $\Delta$ H =-118 kJ/mol