14.6 Why is it useful to write the mass action expression with product concentrations in the numerator? Written this way, the value of Kc gives us information about how far the reaction proceeds to completion. What do large and small values of Kc tell us? Large Kc: reaction moves to completion (lots of product formed). Small Kc (e.g. 4.8x10-31 ): hardly any products are formed. Kc = 1: roughly equal concentrations of reactants and products. Give an example of a reaction that has a large value of Kc. For 2H 2 (g) + O 2 (g) ⎯ 2H 2 O(g), Kc = 9.1 x 10 80 . 14.7 State Le Chatelier’s principle. If an equilibrium in a system is upset, the system will tend to react in a direction that will reestablish equilibrium. Which factors can influence an equilibrium? Adding or removing a reactant or product, changing the volume in a gaseous reaction, changes in temperature, presence of a catalyst. How does adding or removing a reactant or product affect an equilibrium? It changes the concentration of a reactant or product (the
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