1

As Wikipedia states, $\ce{Ag+}$ ions are colorless in solution: https://en.wikipedia.org/wiki/Color_of_chemicals

Compounds that I know of containing $\ce{OH-}$ are also colorless or white (such as $\ce{Mg(OH)2}$, which just like $\ce{AgOH}$ is a precipitate). How is it possible then that AgOH has a brown color?

orthocresol
  • 71,033
  • 11
  • 239
  • 410
ernogal
  • 37
  • 2
  • 4
    Well, afaik it is not really a hydroxide - formula is misleading. Either way, you can only use such reasoning when cation and anion are reasonably "separate" and that's not the case. – Mithoron Aug 16 '22 at 16:13
  • 4
    Wikipedia:Don't abbreviate "Wikipedia" as "Wiki"! Otherwise, you can use some fairly simple syntax to correctly typeset chemical formulae: see https://chemistry.meta.stackexchange.com/q/86/16683 for an introduction – orthocresol Aug 16 '22 at 16:18
  • 2
    $\ce{AgOH}$ does not exist. It is spontaneously decomposed into $\ce{Ag2O}$ and $\ce{H2O}$. Anyway, the question is not solved : Why is silver oxide brown ? The same problem can be discussed with $\ce{MnO2}$ which is brown-black, or $\ce{Cu2O}$ which is orange-yellow, $\ce{CuO}$ which is black, $\ce{HgO}$ which is yellow (sometimes orange), and probably a lot of other examples. Why is it so ? – Maurice Aug 16 '22 at 16:57
  • 2
    https://chemistry.stackexchange.com/questions/32019/why-are-hgo-and-cds-compounds-colourful https://chemistry.stackexchange.com/questions/94249/why-is-a-cuscn2-complex-black – Mithoron Aug 16 '22 at 18:01
  • It also depends on the physical state: finely divided materials may have different color than a bulk sample. For example, Ag metal is shiny, (obviously, 'silvery ;-) en masse, but black when finely divided in photographic emulsion. Colloidal gold may be red when coloring glass. – DrMoishe Pippik Aug 16 '22 at 22:55
  • 1
    There is no $\ce{AgOH}$. It is rather $\ce{Ag2O.xH2O}$ – Nilay Ghosh Aug 17 '22 at 01:54

0 Answers0