Introduction to Multiphase Ion Balance
At a certain temperature, there is a balance of dissolution and crystallization between insoluble electrolyte crystals and ions dissolved in the solution. It is called multiphase ion balance, also called precipitation dissolution balance. Multiphase ion balance is also a very important balance in aqueous solution. It also follows the general law of chemical equilibrium, and each multiphase ion equilibrium has a characteristic equilibrium constant. This is called the solubility product constant of the compound.
In a saturated solution of poorly soluble electrolyte, when the temperature is constant, the product of its ion concentration is a constant. The so-called solubility product is expressed in KSP. For MmNn solid ⇄mMn ++ nNm-, when in a multiphase ion equilibrium state, KSP = [Mn +] m [Nm-] n, the size of the solubility product is related to the solubility of the substance. Using the solubility product rule, the mutual conversion of precipitation and dissolution can be performed. You can also use the difference in solubility product to properly control the conditions (such as controlling pH) to achieve the purpose of separating ions.