For a particular isomer of C 8 H 18 , the combustion reaction produces 5093.7 kJ of heat per mole of C 8 H 18 ( g ) consumed, under standard conditions.

Question

What is the standard enthalpy of formation of this isomer of 

Answer 1

Look up standard energy of formation for CO₂(g) x 8; H₂O(g) x 9 and add them together. Then ...

that value - ΔH for C8H18 = -5093.7 and

ΔH formation for C₈H₁₈ = that value + 5093.7