CHEM 111 Lecture Notes - Joule, Exothermic Process, Stoichiometry
Document Summary
This week"s due date is tomorrow at 5 pm. Hrxn is only based on intial and final states. Therefore, we can picture any process for a reaction. The simplest is to think of all bonds breaking then reforming. This is not what actually happens but it works. If a reaction is endothermic, what does that say about the relative stability of the products vs. the reactants: you cannot make a statement regarding their stability, products are more stable, products are less stable. Endothermic takes energy to get to products. Ch4 (g) + 2o2 (g) co2 (g) + 2h2o (g) Pcl3 (l) + cl2 (g) pcl5 (s: +419 kj, exothermic, +243 kj, endothermic, -243 kj, exothermic, -419 kj, exothermic. Sign of hrxn is connected to direction of the reaction. 2h2 (g) + o2 (g) 2h2o (l) hrxn = -572 kj. Hrxn is determined by number of bonds present. 2h2o (l) 2h2 (g) + o2 (g) hrxn = 572 kj.
