At constant pressure the combustion of 250 g of C2H6g releas

At constant pressure, the combustion of 25.0 g of C₂H₆(g) releases 1295 kJ of heat. What is ?H for the reaction given below?
2 C₂H₆(g) + 7 O₂(g) ? 4 CO₂(g) + 6 H₂O(l).

Solution

moles of C2H6=25/30

=0.83333

so Hrxn=-2*1295/0.8333

=-3108.124 kJ/mol