One Way To Test The Salinity Of A Water Sample Is To Add A Few Drops Of Silver Nitrate Solution With A Known Concentration. As The Solutions Of Sodium Chloride And Silver Nitrate Mix, A Precipitate Of Silver Chloride Forms, And Sodium Nitrate Is Left In Solution. Can You Translate These Sentences Into A Balenced Chemical Equation?

Salinity in water is caused by the compound NaCl (common table salt). So, the reaction stated above is actually done to calculate the concentration of NaCl in the water sample.

The reaction between silver nitrate and sodium chloride is:

Aqueous Silver nitrate + Aqueous Sodium chloride ---> Aqueous Sodium nitrate + Precipitate of Silver chloride.

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

This equation shows that one mole of silver nitrate reacts with one mole of sodium chloride to form a mole each of sodium nitrate and silver chloride.

You can determine the salinity of water by two methods.  You can either add silver nitrate to the sample until the precipitate forms and then calculate the moles of silver nitrate used. You could also add silver nitrate to the solution in excess, filter the resulting mixture, dry the precipitate and weigh it to determine moles of silver chloride formed.