Why is the Equilibrium Constant Important?
It is important because it will tell you is reactants or products are favoured at equilibrium.
Quantitative Reaction:
Favors Products:
Favors Reactants:
No Favor:
Quantitative Reaction:
- Kc is very large (Kc > 10)
- Percent reaction is >99%
- Product concentrations are greater than reactants
Favors Products:
- Kc is large (Kc > 1.0)
- Percent reaction is >50%
- Product concentrations are larger than reactant
Favors Reactants:
- Kc is small (Kc < 1.0)
- Percent reaction <50%
- Reactant concentrations are larger than products
No Favor:
- Kc = 1.0
- Equilibrium contains 50% products
- Percent reaction = 50%
Equilibrium Constant Formula
An equilibrium constant is used to determine the completion of a reaction, and also allows the understanding of whether the reaction will favour the products or reactants.
Kc/K/Keq: Equilibrium Constant
aA+bB⇌ cC+dD
A&B=Reactants
C&D=Products
a, b, c, d=molarity (coefficients)
Formula: Kc= [C]c [D]d (divided by reactants) [A]a [B]b
***note: anything is the box [] means concentration***
Kc/K/Keq: Equilibrium Constant
aA+bB⇌ cC+dD
A&B=Reactants
C&D=Products
a, b, c, d=molarity (coefficients)
Formula: Kc= [C]c [D]d (divided by reactants) [A]a [B]b
***note: anything is the box [] means concentration***
Equilibrium Expression Law
To use the equilibrium law you must know the balanced reaction. It is very important to know the state of the elements because it influences that factors that would be included in the formula.
- Solids are omitted because their concentrations don’t change.
- Liquids are omitted but ONLY if there is one in the equations.
- If there is more than one liquid then include all of them in the formula.
- Water is also not included because the concentration is not included.