Changes in concentration affect equilibrium by shifting the reaction to counter the change, according to Le Chatelier’s Principle:
- Increasing the concentration of reactants:
- The system shifts forward to produce more products.
- Increasing the concentration of products:
- The system shifts backward to produce more reactants.
- Decreasing the concentration of reactants:
- The system shifts backward to produce more reactants.
- Decreasing the concentration of products:
- The system shifts forward to produce more products.
In short: The equilibrium always shifts in the direction that tends to restore balance when concentrations change.