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Unformatted text preview: Ch 13: Chemical Equilibrium Part 3 Le Châtelier’s Principle • Let's go back to the Haber process: N 2 ( g ) + 3H 2 ( g ) ¡ 2NH 3 ( g ) • As the pressure increases, the amount of ammonia present at equilibrium increases. • As the temperature increases, the amount of ammonia at equilibrium decreases. • Can this be predicted? • Or, in other words, what happens when we mess with an equilibrium system? • Le Châtelier’s principle : If a system at equilibrium is disturbed (by a change in temperature, a change in pressure, or a change in the concentration of one or more components), the system will shift its equilibrium position in order to relieve or minimize the disturbance. The system will reach a new equilibrium. • Simplistically, you can think of this as meaning that, for every action, there is an opposite reaction. Change in Reactant or Product Concentration • If a chemical system is at equilibrium and we add or remove a product or reactant which is written in the K expression, the reaction will shift the opposite direction to reestablish equilibrium. • For example: N 2 ( g ) + 3H 2 ( g ) ¡ 2NH 3 ( g ) • If H 2 is added while the system is at equilibrium, Q < K ....
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This note was uploaded on 06/25/2008 for the course CHEM 400-401 taught by Professor Dr.samples during the Fall '06 term at American River.
- Fall '06