Slides in this set
Why does Dynamic Equilibrium exist ?
Example: 2SO2 + O2 D 2S03
In a reversible reaction dynamic equilibrium exist when
the rate of the forward reaction is equal to the rate of the
The concentration of the reactants and products don't
The system is dynamic it is in constant motion
There is no observable change, because reactants are
being converted into products and products are being
converted into reactants!
However the equilibrium will remain only when system is
What is le Chatelier's principle?
Le Chatelier's principle
states that when a system
in a dynamic equilibrium is
subjected to a change (ie
temperature, pressure or
concentration), the position
of the equilibrium will shift
to minimise the change.
This applies to any reaction
that is in equilibrium…read more
Applying le Chatelier's principal to concentration
N2 + 3H2 D 2NH3
Changing the concentration on reactants alters rate of
forward reaction. Changing concentration of products
alters the rate of the reverse reaction.
Increasing the concentration of N2 or H2 (the reactants),
the equilibrium will reduce the concentration of reactants
by using it up so more product is made so the
equilibrium shifts to the RHS.
Increasing the concentration of NH3 (the products) will
cause the equilibrium to shift to the left, the rate of the
forward reaction will decrease and forms more reactants.…read more
Applying Le Chatelier's principal to pressure
N2 + 3H2 D 2NH3
(1+3= 4 moles) (2moles)
A change in pressure depends on total moles of gas on
each side of the reaction:
Increasing the pressure will cause the equilibrium to
move from where there are more gas molecules to
where there are fewer thus lowering the pressure
Decreasing the pressure will cause the equilibrium to
shift to where there are more gas particles according
to le chatelier's principal…read more
Applying le Chatelier's principal to Temperature
Increase in temperature:
The key is that a change in temperature will depend on
whether the forward reaction is exothermic or endothermic:
N2 + 3H2 = 2NH3 (forward reaction: exothermic, reverse
If there is temperature is increase, according to le Chatelier's
principal; the reaction will reverse this by decreasing the
temperature this is achieved by favouring the endothermic
reaction so the equilibrium shifts left.
If there is a decrease in temperature the reaction will reverse
this by increasing the temperature of the reaction. This will be
achieved by favouring the exothermic reaction and thus the a
shift to the right.…read more