what can it be?

[arthur kierski]

when i put some copper in a solution where pms where already precipitated (barren solutions),nitric solution for silver and pd,ar for gold,i obtain a white powder(sometimes)--------- i thought that only pms not precipitated totally would drop with the copper and not this strange white powder---could someone tell me what this white powder can be?

 

[leavemealone]

if it doesn't dissolve in water it may be silver.But hard to tell without knowing what you put in it and the steps you've taken til now.
Johnny

 

[lazersteve]

Filter some of the powder out and let it sit in the open air.

1. Does it change colors?

2. Does it dissolve in straight HCl?

If yes to 1 or 2 above could be copper I chloride.

Steve

 

[butcher]

As Steve suggests copper 1 chloride usually changes greenish when dried in air, and will dissolve in HCl.
silver can change colors also in wet solutions in light also usually a violet color, silver chloride will not dissolve in hot water, or dilute straight HCl.
lead chloride will dissolve in boiling hot water and precipitate when cooled.
Salts from the chemicals are also possible, and white powders can be a combination's of all of these, as Johnny says depending on what's added and process used.