1. The problem statement, all variables and given/known data Question: What kinds of ions may co-precipitate with a chloride ion? (List at least two). This is a question for the theory section of my gravimetric analysis lab. An unknown chloride salt is mixed into a solution. This solution is to be mixed with a certain quantity of silver nitrate to precipitate out silver chloride, but first the solution is mixed with nitric acid to ensure that no unwanted co-precipitates form. Specifically, the nitric acid is mixed in to ensure that any carbonate ions that may be present within the solution are converted to carbon dioxide gas and water (if somebody could tell me why carbonate ions would even be in this solution in the first place, that'd be awesome too). Otherwise, carbonate ions may precipitate to form silver carbonate and the analysis will be ruined. 2. Relevant equations I know that in this solution, there are H+ ions, Ag+ ions, Cl- ions and NO3-- ions. What I'm trying to find are two ions that may form a precipitate with Cl-. 3. The attempt at a solution I've only been able to find 1 possibility so far, being the formation of NH4Cl. NH4+ + Cl- --> NH4Cl Thanks ahead of time for any/all help given.