Butane (C4 H10(g), Delta. Hf = –125. 6 kJ/mol) reacts with oxygen to produce carbon dioxide (CO2 , Delta. Hf = –393. 5 kJ/mol ) and water (H2 O, Delta. Hf = –241. 82 kJ/mol) according to the equation below. 2 upper C subscript 4 upper H subscript 10 (g) plus 13 upper o subscript 2 (g) right arrow 8 upper C upper O subscript 2 (g 0 plus 10 upper H subscript 2 upper O (g). What is the enthalpy of combustion (per mole) of C4H10 (g)? Use Delta H r x n equals the sum of delta H f of all the products minus the sum of delta H f of all the reactants. -2,657. 5 kJ/mol –5315. 0 kJ/mol –509. 7 kJ/mol –254. 8 kJ/mol.