# Question 675a3

Nov 29, 2015

["Ag"("NH"_3)_2]^(+)

#### Explanation:

First thing first, you can read about the double replacement reaction that takes place between sodium hydroxide, $\text{NaOH}$, and silver nitrate, ${\text{AgNO}}_{3}$ here

http://socratic.org/questions/what-is-naoh-nacl-low-solubility-or-high-solubility-does-it-precipitate-note-no-

Now, this double replacement reaction will produce silver oxide, $\text{Ag"_2"O}$, an insoluble solid that precipitates out of solution.

Silver oxide's solubility actually increases upon addition of ammonia to the solution. This is why the solution goes from brown to colorless. So, the balanced chemical equation for the double replacement reaction is

$2 {\text{Ag"_text((aq])^(2+) + 2"OH"_text((aq])^(-) -> "Ag"_2"O"_text((s]) darr + "H"_2"O}}_{\textrm{\left(l\right]}}$

Adding ammonia will result in the formation of the diamminesilver(I) cation, ["Ag"("NH"_3)_2]^(+)#. The net ionic equation for the reaction looks like this

${\text{Ag"_2"O"_text((s]) darr + "H"_2"O"_text((l]) + 4"NH"_text(3(aq]) -> 2["Ag"("NH"_3)_2]^(+) + 2"OH}}_{\textrm{\left(a q\right]}}^{-}$

Because ammonia is a neutral molecule, the complex ion will retain the $\left(+ 1\right)$ charge of the silver cation.

This reaction is used to get Tollen's reagent, a chemical reagent used to test for the presence of ketones and aldehydes - the famous "silver mirror" reaction $\to$ read more on that here

http://www.chemguide.co.uk/organicprops/carbonyls/oxidation.html