# silver chloride filtration



## ericrm (Oct 31, 2012)

can someone tell me what size of whatman filter paper would retain *all* silver chloride particle precipitated with water and ice?


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## MysticColby (Oct 31, 2012)

I use Whatman #2 (8 µm) and have never seen any silver chloride or cemented silver go through it (I've filtered both)
If you're worried about getting the last 0.1% that is invisible to the naked eye, you can step it up to #3 (6 µm) or #5 (2.5 µm). But filtration time on those is 35% and 490% longer, respectively.

it might depend on how you made your silver chloride... I've always used NaCl. It always looks like particles of AgCl - quite big compared to, say, cemented silver. If you made it with HCl, maybe it's a different particle size?

Sometimes I even use just a coffee filter, and get the same visual confirmation of getting everything.





There are some solutions these don't work for, so don't trash your filtrate before you know they work.


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## flyfisherman (Oct 31, 2012)

Does coffee filters work as good as filter paper,and if so what is the point of of using more expensive Whatman?


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## cnbarr (Oct 31, 2012)

flyfisherman said:


> Does coffee filters work as good as filter paper,and if so what is the point of of using more expensive Whatman?



They can work as good under certain circumstances, but 90% of the time they won't, especially during vacuum filtration. The weave in a. Coffee filter isn't as precise as that of a whatman or equivalent,. Multiple layers of coffee filters will tend to float trapping particles between the layers or worst case tearing under the vacuum pressure.


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## ericrm (Oct 31, 2012)

the best way to see the difference is: take a coffee filter and put it in front of a light , you will see tiny star of light in it ,lab filter paper doesnt...
that doesnt mean that coffee filter arent good ,i have bought 10pack at 3$ each and i use them constently.
coffe filter are very good to remove "chunk " of material (like with disolve gold from finger to remove bits of plastic and such) but silver chloride precipitated from aqua regia with whater and ice is very thin (it feel like trying to filter milk it just goes right thru the filter)


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