1. The problem statement, all variables and given/known data Calculate ΔH°rxn in kJ/mol for: C3H8(g) + 4 CO2(g) + 4 H2(g) → C7H16(g) + 4 O2(g) from the following given values of ΔH°rxn: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g) ΔH°rxn= -2,010 kJ/mol C7H16(g) + 11 O2(g) → 7 CO2(g) + 8 H2O(g) ΔH°rxn= -4,426 kJ/mol H2(g) + ½ O2(g) → H2O(g) ΔH°rxn= -241.8 kJ/mol 2. Relevant equations None 3. The attempt at a solution I swapped the middle to give +4,426 kJ/mol. Then I tried multiplying the middle by 1/2 and the third one by 4. Am I on the right track? Anything else need to be swapped? I feel like the next step should be obvious; I'm just stuck.