CHEM 111 Lecture Notes - Enthalpy, The Review Show, Joule
Document Summary
All open now, close 12 / 15 at 6 pm. Rooms close at 7:30 am, do not be late. When coefficients are divided, hrxn"s are as well. The hrxn of an overall reaction is the sum of the hrxn values of individual steps. Ch4 (g) + 2o2 (g) co2 (g) + 2h2o (g) hrxn = -802 kj. Ch4 (g) + 2o2 (g) co2 (g) + 2h2o (l) hrxn = -890 kj. How to calculate unknown hrxn: note the coefficients of the target reaction, manipulate equations with known hrxn to match target reaction. Multiply coefficients and hrxn by the same factor: add reactions and hrxn values to get the target reaction and unknown hrxn. 2nocl (g) n2 (g) + o2 (g) + cl2 (g) N2 (g) + o2 (g) no (g) hrxn = 90. 3 kj. No (g) + cl2 (g) nocl (g) hrxn = -386 kj. Nocl (g) no (g) + cl2 (g) hrxn = 386 kj.
