Effect of Concentration Changes on the Position of Equilibrium

The position of equilibrium in a chemical reaction can be affected by changes in the concentration of the reactants and products.

  • If the concentration of a reactant increases, the position of equilibrium shifts to the right. This will counteract the increase in concentration of the reactant by producing more product.
  • If the concentration of a product decreases, the position of equilibrium will shift to the right. This will produce more product to counteract the decrease in concentration.

Conversely, if the concentration of a product on the right side of the equation increases or the concentration of a reactant on the left side of the equation decreases, the position of equilibrium will shift to the left.

Example

Let’s look at a reversible reaction:

2NO2 ⇌ N2O4

If we increase the concentration of 2NO2, the position of equilibrium will shift to the right. This will produce more N2O4 to counteract the increase in reactant concentration.

On the other hand, if we increase the concentration of N2O4, the position of equilibrium will shift to the left. This will produce more NO2 to counteract the increase in product concentration.