Final answer:
The color of a precipitate formed in a reaction can vary and is useful for identifying the ions present in a solution, such as a yellow precipitate indicating lead iodide or a white precipitate for chloride ions with silver nitrate.
Step-by-step explanation:
When a reaction occurs with a known ion that produces a precipitate, the color of the precipitate can vary based on the reactants involved. For instance, when a colorless solution of lead (II) nitrate is added to a colorless solution of potassium iodide, a yellow precipitate of lead iodide is formed. This yellow precipitate is an indication that a chemical reaction has occurred, where a solid product called a precipitate is produced and settles out of the liquid solution. In another example, when silver nitrate (AgNO3) is added to a solution of an unknown potassium salt, a white precipitate could form if chloride ions are present. The color of precipitates can therefore be used to help identify the ions in a solution.