Filter then urea or urea then filter

[Dr. Poe]

ok, after a web search and quick look through a couple of books, it says that gold trichloride decomposes in light and is hygroscopic(pulls water from the air). is this true for all AuCl compounds? sorry about the questions but its hard to understand all the text in my chemistry books.

With exception of sulfides, selenides and tellurides (which have a stable valency of +2) Gold ions are most stable at +3.
The +1 valency of AuCl is unstable and tends to decompose into 2 parts of +0 and one part of +3.
3 AuCl -> 2 Au + AuCl3 Au+1 gives 1.68 volts in reduction whereas Au+3 only gives 1.44 volts on reduction.
Gold oxides, sulfides, selenides and tellurides hate water (hydrophobic) where the trivalent gold chlorides, bromides tend to love water and are hygroscopic to 4 waters of crystallization. Of the halogens, only the iodides hate water and the fluorides are decomposed by water ( as are also the sulfates). The gold iodides love solutions of potassium iodide, but hate everything else. In contrast, the thiosulfates (AKA thionates) love water, acids and alkali solutions. Does this clear thing s up a bit?
Some believe that +2 gold ions are in reality a mix of +1 and +3 (not me).
Dr. Poe