Presentation on theme: "When do you use this? You use Keq to find the concentration of a reversible reaction at equilibrium. You use Q to find the concentration of a reversible."— Presentation transcript:
When do you use this? You use Keq to find the concentration of a reversible reaction at equilibrium. You use Q to find the concentration of a reversible reaction at a given time before equilibrium to know in which direction the reaction goes.
What are the definitions? Keq: Law of mass action express the relative concentration of reactants and products at equilibrium in terms of quantity called the equilibrium constant Q: The reaction Quotient of Keq
Steps/Rules Keq: 1. Balance the equation 2.Put the products on top and the reactants on the bottom 3.coefficients are exponents 4.only use (g) and (aq) 5. Use the M of reactants and products to find keq. Keq>>1= reaction lies to the right Keq<<1= reaction lies to the left Keq=1 at equilibrium
More Steps and Rules Q: 1. Do all for Keq 2.Use given M at given temperature. 3.Compare with value of Keq. QKeq= reaction lies to the left (reactant side)
A solved EXAMPLE (Keq) 2CO(g) + O2 (g) 2CO2 (g) Keq = [CO2]^2/ [CO]^2 [O2] (Q) COCL2(g) CO(g) Cl2(g) and Keq =170. If the concentration of CO and C2 are each 0.15M and the concentration of COCL2 is 1.1 x 10^-3 is the reaction at equilibrium? [CO][Cl2] / [COCl2] = (.15)(.15)/1.1x10^-3 = 20 Q=20
Here's Something to SOLVE >:) Keq: NH4NO3 (s) N2O(g) + H2O Q: At 448 degrees C K= 50.5 for the reaction H2(g) + I2(g) 2HI (g), Find Q and the direction of the reaction of the reaction if [H2] =.15 M, [I2] =.175 M, [HI] =.950 M.
Here are the answers Keq = [N2O][H20]^2 Q= Reaction lies to the right.