# Extracting silver from Tollens test

When we add tollens reagent (diamminesilver(I) cation, $\ce{[Ag(NH3)2]+}$) to glucose it forms a silvery mirror on the walls of the container. Since the sides are coated with actual Silver,

1. is there any possible reagent/method to take the silver out from the sides of the test tube.?

2. will it be in its pure form or will there be organic/inorganic impurities?

## 2 Answers

1. Silver's pretty soft—it's possible to just scrape it off with a metal spatula or something. Also, not all of the silver deposits on the glass. You might be able to adjust the conditions of the reaction to make more silver precipitate into the liquid where it's easier to get at. You can, of course, redissolve the silver in nitric acid or the like.

2. Since the byproducts of the reaction are soluble, it should be pretty pure, depending on how pure the starting materials are. If other easily reducible metal cations are present, you might get some impurities from that.

As a side-note, this isn't a particularly efficient way of getting elemental silver. The typical films produced in a test tube probably contain a couple hundred milligrams at most. Even a whole undergrad lab's worth of tubes is probably not worth recovering.

1) Silver is pretty easily dissolved in concentrated nitric acid (attention, nitrogen oxides fumes). The resulting solution may be gently evaporated to get rid of excess of nitric acid and silver nitrate may be then reduced with zinc and then washed from excess zinc with diluted sulfuric acid. Alternatively, silver nitrate may be used as is for similar tests in future.

2)As Michael noted, it is pretty pure.