CALCULATE EQUILIBRIUM
CONSTANT AND THE PRESSURE
OR CONCENTRATION OF
REACTANTS IN AN EQUILIBRIUM
MIXTURE
MA. ISABELLA ARTIAGA
ANGEL BUCAYO
The Equilibrium Constant, K
The equilibrium constant, K, is the numerical
value that is obtained when equilibrium
concentrations are substituted to the
equilibrium constant expression. The value of K
may vary from very large to very small values.
This value provides an idea of the relative
concentrations of the reactants and products in
an equilibrium mixture.
REMEMBER:
 If K >> 1 (large K value), the equilibrium lies to the
right and the products predominate in the equilibrium
mixture.
 If K << 1 (small K value), the equilibrium lies to the
left and the reactants predominate in the equilibrium
in the equilibrium mixture.
Calculating K when all equilibrium
concentrations/partial pressures are known
Determining equilibrium constants when
equilibrium concentrations or partial pressures
are known involves straightforward substitution
to the equilibrium constants expression.
Calculating K from initial and equilibrium
concentration/partial pressures
In most cases, what is known to the experimenter is the
equilibrium constant at a certain temperature and the initial
concentrations or partial pressures of the species present. This
means that equilibrium quantities must be determined before
calculating for K. This can be done by treating the change as a
variable where the stoichiometric coefficients from the
balanced equation can be used to denote the relationship
between the changes in the concentration/partial pressure of
the reactants and products.
Calculating equilibrium concentrations/partial
pressures from initial concentrations/partial pressures
and K values
Example:
CALCULATE EQUILIBRIUM
CONSTANT AND THE PRESSURE
OR CONCENTRATION OF
PRODUCTS IN AN EQUILIBRIUM
MIXTURE
LUIGI NICOLAI SACE
GIL JANE CABANIG
Keep In Mind
REMEMBER:
 If K >> 1 (large K value, the value is above 1), the
equilibrium lies to the right and the PRODUCT
predominate in the equilibrium mixture.
 If K << 1 (small K value, the value is below 1), the
equilibrium lies to the left and the REACTANTS
predominate in the equilibrium in the equilibrium
mixture.
Equilibrium the concentration of N2O4 is 0.2 M and
the concentration of NO2 is 0.05 M
Find the Kc
2NO2(g) ⇌ N2O4(g)
Equilibrium Constant Formula:
Substitute the given values:
Kc = [N2O4]
————
[NO2]²
Kc = [0.2M]
————
[0.05M]²
=
80M^-1
The Value 80M^-1 is K>>1 (Higher value than 1) so the
PRODUCT predominate in the equilibrium mixture
REACTANT
PRODUCT
2NO2(g) ⇌ N2O4(g)