okay so this video is how we test for bromide and chloride ions using silver nitrate so we're gonna have a look at the experiment first today here's my sample of chloride ions the first thing I need to do to it is to add a small amount of nitric acid just to remove impurities or Goods no clean so in case they carbonate or stuff like that in there so that it reacts and won't react with the reagents the main thing that's gonna test to my chloride and bromide ions is silver nitrate solution we store these in these brown bottles because it breaks down in the presence of light so that means that it lasts a little bit longer so with chloride ions when I add the silver nitrate you can see that it makes this really bright white precipitate now I haven't looked at the bromide by contrast the bromide also looks like it produces a white precipitate but if I compare them side-by-side I hope you can see the chloride one this one is much whiter than the bromine so we say the chloride makes a white precipitate the bromide makes a cream precipitate so let's check out the equations and how those precipitates actually form okay so here's my unknown solution and if I'm testing for br- or CR - the first thing that you do is you add dilute nitric acid just like I did to remove those impurities now if you're smart and you've been paying attention then you've probably realized that most of the time I use hydrochloric acid so you should be say hold up why are using nitric acid here now the reason is is that hydrochloric acid contains chloride ions so if I use hydrochloric acid to remove impurities what I'm really doing is adding chloride ions into my sample which means that I'll get a false positive result no matter what was there to start with so the second step of the reaction is that you add silver nitrate solution which is AG no.3 and that reacts with my chloride ions which might be in the form of KCl it could be NaCl anything bonded with a chloride and it makes a G CL and kno3 in a displacement reaction now the thing that causes your white precipitate is always your silver chloride solution the bromide one works in almost exactly the same way apart from your cream precipitate is coming from the silver bromide solution if you're getting confused about which of the products is responsible for the precipitate just remember what you're testing for in this case you're testing for bromide and chloride so that means the product that contains those has got to be the one that's causing the precipitate