What is common ion effect? What does it refer to? How is common ion effect related to Le Chatelier’s principle? This article shall answer the above questions while providing all the related information. Let us get started.
Adding a soluble compound that shares an ion with a precipitate reduces the solubility of the precipitate, which is known as the common-ion effect. This behavior is a result of Le Chatelier’s principle for the ionic association/dissociation equilibrium reaction. Increasing the concentration of one of the salt’s ions causes the solubility of salts and other weak electrolytes to decrease, leading to increased precipitation and the eventual reaching of the salt’s solubility equilibrium. The presence of both the original salt and a second additional chemical with a shared ion causes this effect.
The role of the common ion effect in solutions is most obvious in the reduction of solid solubility. Because of a shift in equilibrium, the solubility of a chemical drops when common ions are added. The common ion effect is also involved in buffer management. An acid or base is present in buffering solutions, along with its conjugate counterpart. The pH of the solution will eventually shift as additional similar conjugate ions are added. When evaluating solution equilibrium after adding ions that are already present in the solution, the common ion effect must be taken into account. The common-ion effects are beneficial to the salting-out procedure used in soap production. Soaps are fatty acid sodium salts. The solubility of the soap salts is reduced when sodium chloride is added. A mixture of common-ion action and higher ionic strength causes the soaps to precipitate.
When gaseous hydrogen chloride is circulated through a sodium chloride solution, the excess chloride ions in the solution cause the NaCl to precipitate, which is an example of the common ion effect. In transition metal complexes, this effect is not observed. This is due to the d-block elements’ proclivity for forming complexions. Cuprous chloride, which is water-insoluble, is a prime illustration of this. The addition of chloride ions to this molecule causes the CuCl2– complex-ion to form, which is soluble in water.
In this article, we’ll look at how the addition of a common ion affects the solubility of a salt in a solution.
However, water with a sensible number of Na+ ions, such as saltwater and brackish water, might impede the action of soaps by diminishing their solubility and hence their activity.
The common ion effect is a phenomenon where the solubility of a salt decreases when another compound, having a common ion, is added to the solution. This happens because the extra ions suppress the dissociation of the salt due to Le Chatelier’s principle.
The common ion effect occurs when a compound shares an ion with the dissolved salt. For example, if NaCl is added to a solution of HCl, the common ion is Cl⁻. The additional Cl⁻ ions reduce the dissociation of HCl, making the solution less acidic.
In acids, the common ion effect occurs when an acid's dissociation is suppressed by adding a compound that provides the same ion as the acid. For example, adding sodium acetate (CH₃COONa) to acetic acid (CH₃COOH) reduces the dissociation of acetic acid because both release the common ion CH₃COO⁻.
