The aqueous solutions of silver nitrate and sodium chloride are combined together, such that silver and chloride ions react and form an insoluble white precipitate, called silver chloride (AgCl). The chemical equation associated is:
NaCl + AgNO3 -> AgCl + NaNO3
The ionic equation is:
Na^+ + Cl^- + Ag^+ + NO3^- -> AgCl + NO3^- + Na^+
Reducing like ions from both sides, reactants and product, yields the net ionic equation:
Cl^- + Ag^+ -> AgCl
The problem that occurs when there exists reaction having silver ions involved, is that there could be possible interferences, such that thiocyanate ions, which also form white precipitate with silver solution.
If the presence of thiocyanate ions is proved, then they must be removed by oxidation, hence, before silver chloride to be formed, it must be added into solution nitric acid (HNO3), and then the interference is solved.