Lesson 4b ­ Quantitative Changes in Equilibrium Systems (More Complex)December 09, 2014
7.5 ­ Quantitative Changes in Equilibrium Systems
More Complex Scenarios
In more complex scenarios, we can sometimes simplify the equation by making the assumption that x will have a negligible effect on the change in some concentrations. If the change is less than 5% off, it is a valid assumption. We use the “hundred rule” to determine if a simplifying assumption is warranted. Example #1: Calculating equilibrium concentrations when K is very small (imperfect squares)
Nitrosyl chloride, NOCl decomposes to form nitrogen monoxide and chlorine gas according to the following equation:
2 NOCl (g) 2 NO (g) + Cl2 (g)
At 35 Celsius, Keq is 1.60 x 10­5 . Calculate the concentration of all entities at equilibrium if 0.80mol NOCl is placed in an evacuated 2.00L container at this temperature and allowed to reach equilibrium.
Lesson 4b ­ Quantitative Changes in Equilibrium Systems (More Complex)December 09, 2014
Example #2: Calculating equilibrium concentrations involving a Quadratic equation.
When hydrogen and iodine are placed in a closed container at 440 Celsius, they react to form hydrogen iodide. At this temperature, the equilibrium constant, K is 49.7. Determine the concentrations of all entities at equilibrium if 4.00 mol of hydrogen and 2.00 mol of iodine are placed in a 2.00 L reaction vessel.