1. Dynamic Equilibrium and the Equilibrium Constant
Dynamic Equilibrium and the Equilibrium Constant

2. Dynamic Equilibrium
State in which rate of forward reaction = rate of reverse reaction
Concentrations of reactants & products are fixed
Not inherently equal
Reaction continues to occur, just at constant rate

4. Equilibrium Constant
Ratio of concentrations of products raised to their stoichiometric coefficients, divided by concentration of reactants raised to their stoichiometric coefficients
Used to quantify concentration of reactants and products at dynamic equilibrium
Uses denotation K
Non-italicized K for Kelvins
aA + bB cC + dD

5. Law of Mass of Actions How to figure out equilibrium constant [C]c[D]dK=
[A]a[B]b
Does not indicate speed of reaction, only how far along reaction is when it hits dynamic equilibrium
aA + bB cC + dD

6. Practice
2NO2 ⇌ N2O4
H2SO4 ⇌ 2 H+ + SO42-

7. Significance of Equilibrium Constant
K < 1 : reverse reaction is favored, forward reaction does not go very far
K = 1 : neither direction is favored, forward reaction goes about halfway
K > 1 : forward reaction is favored, forward reaction proceeds essentially to completion

8. Relationship Between Equilibrium Constant and Chemical Equation
1. If equation is reversed, invert
constant
Kreverse = 1/ Kforward = K’
2. If coefficients are multiplied by a common factor, raise equilibrium constant to same factor
3. If adding two or more individual chemical equations, multiply corresponding equilibrium constants by each other to obtain one equilibrium constant

9. Practice
Consider following chemical reaction and equilibrium constant at 25 degrees C
2COF2(g) CO2(g) + CF4(g) K = 2.2 x 106
Calculate equilibrium constant for following reaction at 25 degrees C
2CO2(g) + 2CF4(g) COF2(g) K’ = ?

10. Practice
Consider chemical equation and equilibrium constant for synthesis of ammonia at 25 degrees C
N2(g) + 3H2(g) NH3(g) K = 5.6 x 105
Calculate equilibrium constant for following reaction at 25 degrees C
NH3(g) /2 N2(g) + 3/2 H2(g) K’ = ?