A double replacement reaction occurs when the cations and anions of two ionic compounds exchange places, resulting in the formation of two new compounds. In this case, the reaction involves potassium chloride KCl and silver nitrate AgNO3 . The chemical equation for this reaction can be written as:KCl aq + AgNO3 aq KNO3 aq + AgCl s In this reaction, potassium K+ from potassium chloride exchanges its anion with silver Ag+ from silver nitrate, forming potassium nitrate KNO3 and silver chloride AgCl . The aq notation indicates that the compounds are in aqueous solution, meaning they are dissolved in water.The formation of a precipitate occurs when one of the products of the reaction is insoluble in water. In this case, silver chloride AgCl is the insoluble product, which means it does not dissolve in water and forms a solid precipitate. The solubility rules indicate that most chloride salts are soluble, except for those containing silver Ag+ , lead Pb2+ , and mercury Hg2+ . Therefore, when potassium chloride and silver nitrate are mixed together, a precipitate of silver chloride forms.The balanced chemical equation for this reaction, including the state symbols, is:KCl aq + AgNO3 aq KNO3 aq + AgCl s This equation shows that when potassium chloride KCl and silver nitrate AgNO3 are mixed together in an aqueous solution, a double replacement reaction occurs, resulting in the formation of soluble potassium nitrate KNO3 and an insoluble precipitate of silver chloride AgCl .