When silver nitrate (AgNO3) is added to salt water (NaCl), a chemical reaction takes place, resulting in the formation of a white precipitate of silver chloride (AgCl) and sodium nitrate (NaNO3). This reaction can be represented by the following equation:

AgNO3(aq) + NaCl(aq) -> AgCl(s) + NaNO3(aq)

In this reaction, the silver ions (Ag+) from the silver nitrate combine with the chloride ions (Cl-) from the sodium chloride, forming insoluble silver chloride. The sodium and nitrate ions remain in solution as sodium nitrate. The formation of a new substance (silver chloride) indicates that a chemical change has occurred.