Question

Lexan is a plastic used to make compact discs, eyeglass lenses, and bullet-proof glass. One of the compounds used to make Lexan is phosgene (COCl2), a poisonous gas. Phosgene is produced by the reaction CO(g) 1 Cl2(g) 34 COCl2(g) for which K 5 4.5 3 109 at 100.8C. a. Calculate Kp at 100.8C. b. Equal moles of CO and Cl2 are reacted at 100.8C. If the total pressure at equilibrium is 5.0 atm, calculate the equilibrium partial pressures of all the gases.

Option 1: Kp = 4.5 x 10^9; Partial pressures: CO = 2.5 atm, Cl2 = 2.5 atm, COCl2 = 0 atm
Option 2: Kp = 9 x 10^9; Partial pressures: CO = 1.5 atm, Cl2 = 3.5 atm, COCl2 = 0 atm
Option 3: Kp = 4.5 x 10^9; Partial pressures: CO = 3.0 atm, Cl2 = 2.0 atm, COCl2 = 0 atm
Option 4: Kp = 9 x 10^9; Partial pressures: CO = 2.0 atm, Cl2 = 3.0 atm, COCl2 = 0 atm

Answer 1

The correct value of Kp at 100.8°C is 4.5 x 10^9 as given in the question. However, the calculated equilibrium partial pressures in the provided options are not feasible with this high Kp value, indicating an error in the options.

Step-by-step explanation:

The question relates to the calculation of the equilibrium constant (Kp) and the determination of equilibrium partial pressures for a chemical reaction involving CO, Cl2, and COCl2 at a specific temperature. Given the reaction CO(g) + Cl2(g) → COCl2(g) and the value of the equilibrium constant K at 100.8°C, we can say that the equilibrium constant for the reaction in terms of pressure (Kp) is provided as 4.5 x 109. Therefore, option a gives the correct Kp value directly.

To find the equilibrium partial pressures, we set up an ICE table (Initial, Change, Equilibrium). Since the reaction has a large K value, it proceeds nearly to completion. At equilibrium, the partial pressure of COCl2 will be close to the total pressure minus very small amounts of CO and Cl2 left, due to the stoichiometry of the reaction. The partial pressures of CO and Cl2 at equilibrium will thus be very small compared to the partial pressure of COCl2. None of the options presented provide a plausible set of equilibrium partial pressures given the large Kp value, suggesting an error in the provided options.