A few drops of AgNO3 is added to a sample of the unknown. A white precipitate appears. Which ion is present?

More than likely it is Cl^- but I would want to do one or two confirmatory tests to make sure.

To determine which ion is present in the unknown sample when a white precipitate forms after adding a few drops of AgNO3 (silver nitrate), we need to understand the reaction that takes place.

When AgNO3 is added to a solution containing certain ions, it can result in the formation of different precipitates depending on the specific ion present. In this case, a white precipitate indicates the presence of chloride ions (Cl-) in the solution.

The reaction between silver nitrate (AgNO3) and chloride ions (Cl-) can be written as follows:

AgNO3 + Cl- -> AgCl(s) + NO3-

The white precipitate that forms is silver chloride (AgCl), which is insoluble in water and appears as a solid.

By observing the formation of the white precipitate after adding AgNO3, we can conclude that chloride ions (Cl-) are present in the unknown sample.