What is the effect of decreasing the pressure of a reaction mixture at equilibrium if the reactant side has fewer moles of gas particles than the product side?
When a system at equilibrium undergoes a change in pressure, the equilibrium of the system will shift to offset the change and establish a new equilibrium. The system can shift in one of two ways:
- Toward the reactants (i.e. in favor of the reverse reaction)
- Toward the products (i.e. in favor of the forward reaction)
The effects of changes in pressure can be described as follows (this only applies to reactions involving gases):
- When there is an increase in pressure, the equilibrium will shift towards the side of the reaction with fewer moles of gas.
- When there is a decrease in pressure, the equilibrium will shift towards the side of the reaction with more moles of gas.
Pressure is inversely related to volume. Therefore, the effects of changes in pressure are opposite of the effects of changes in volume. Additionally, this does not apply to a change in the pressure in the system due to the addition of an inert gas.