Keq vs. Q

1. Keq vs. Q Monsurat Olaosebikan Nicole Gomez Johan Mann

2. Keq • Keq is the equilibrium constant which measures the extent to which a reaction proceeds to completion. Q • Q is the reaction quotient used to determine if the reaction is at equilibrium.

3. Equations! • Keq= [C]c[D]d [A]a[B]b aA + Bb cC + dD Q follows the same rule, except that the variables are replaced with the corresponding concentrations of the substances. If Q<Keq the reaction proceeds to the right in the direction of the products and is not at equilibrium. If Q>Keq the reaction proceeds to the left in the direction of the reactants and is not at equilibrium. If Q=Keq the reaction is at equilibrium.

4. Example CO2 + H2 • For the reaction CO + H2O a)Calculate Q given the following concentrations [CO] = 2.15M, [H20]=2.05M,[H2]=2.4M,[CO2]=0.37M and Keq=5.1 b)In which direction will the reaction proceed. Keq= [CO2][H2] [CO][H2O] Q= [0.37][2.4] [2.15][2.05] = 0.2014 Since Q<Keq it the reaction proceeds to the right. 0.2<5.1

5. Practice Problem 2NO2, Keq= 0.2 • For the reaction N2O4 At a particular time the following concentration are measured: N2O4= 2.0 M NO2= 0.2 M. Find Q and the direction it proceeds.

6. Solution Keq= [NO2]2 [N2O4] Q= [0.2]2 [2] = 0.02 Since Q<Keq it the reaction proceeds to the right. 0.02<0.2