Multiply third equation by 4 Combine and cancel 3C(s) + 3O2(g) 3CO2(g) H = 3(-394 kJ) → 4H2(g) + 2O2(g) 4H2O(g) H = 4(-286 kJ) → 4H2O(g) + 3CO2(g) C3H8(g) + 5O2(g) H = +2220 kJ → 3C(s) + 4H2(g) C3H8(g) H = - 106 kJ →
Multiply third equation by 4 Combine and cancel 3C(s) + 3O2(g) → 3CO2(g) H = 3(-394 kJ) 4H2(g) + 2O2(g) → 4H2O(g) H = 4(-286 kJ) 4H2O(g) + 3CO2(g) → C3H8(g) + 5O2(g) H = +2220 kJ 3C(s) + 4H2(g) → C3H8(g) H = - 106 kJ
1211-exam-II-fall09-withanswers.docx