Effect of Change in Concentration

Le Chatelier's principle states that if a system at equilibrium is subjected to a change in conditions, the position of equilibrium shifts in the direction that tends to oppose the change.For concentration:• Increasing the concentration of a reactant shifts the equilibrium to the right, using up some of the added reactant and making more product.
• Removing a product shifts the equilibrium to the right, replacing some of the product.
• Increasing the concentration of a product, or removing a reactant, shifts the equilibrium to the left.Example. Yellow chromate(VI) ions and orange dichromate(VI) ions are in equilibrium in solution:2CrO₄²⁻(aq) + 2H⁺(aq) ⇌ Cr₂O₇²⁻(aq) + H₂O(l)yellow                  orangeAdding acid increases [H⁺]. The equilibrium shifts to the right to remove some of the H⁺, so the solution turns more orange.Adding alkali removes H⁺ ions (OH⁻ + H⁺ → H₂O). The equilibrium shifts to the left to replace them, so the solution turns more yellow.Industry uses this idea: removing a product as it forms, or using an excess of a cheap reactant, increases the yield of the product.A change in concentration changes the position of equilibrium but does not change the value of the equilibrium constant, K_c, at a given temperature.