gravimetric analysis question...
 

why is the precipitate washed until it is chloride free? how can chloride ion in the filtrate be tested for?

thx 1st

I don't know the answer for the first part, but for the second part (if i'm not mistaken :wink: ) you must use acidified aqueous AgNO3 and aqueous NH3(dilute) If the white precipitate formed is completely soluble in dilute NH3 then it means the filterate contains Cl- ion.

Chloride ions have mass. Gravimetric analysis is about determining mass. You want the mass of something other than the chloride ions I imagine.