Talk:Tollens' reagent

What is the reagent?[edit]

I am no expert but the following prep looks strange:

2 AgNO₃ (aq) + 2 NaOH (aq) → Ag₂O (s) + 2 NaNO₃ (aq) + H₂O (l)

Ag₂O (s) + 4 NH₃ (aq) + 2 NaNO₃ (aq) +H₂O (l) → 2 Ag(NH₃)₂NO₃ (aq) + 2 NaOH (aq)

Why make Ag2O if the product is the nitrate. My ancient qualitative organic text gives the formula Ag(NH₃)₂OH but the authors (including Reynold C. Fuson) probably did not care about the detailed structures of their reagents. Hydroxides of Ag+ are rare (we once had an article on AgOH but it was merged due to the flimsy evidence for the cmpd).--Smokefoot (talk) 22:14, 14 February 2009 (UTC)[reply]

The error seems to be in the presentation rather than the chemistry. The description of the prep given in the article agrees with my memory of the prep. What you don't do, of course, is convert all your silver to silver oxide, otherwise you'll have a job getting it back into solution again! Instead, you add strong base (NaOH) to ensure a basic pH (don't forget that silver nitrate solution is usually prepared in dilute nitric acid, not distilled water), just enough to start the silver coming out of solution, and then add ammonia to redissolve it. Putting that into balanced stoichiometric equations separated from the description of the procedure is what (I think) is causing the confusion. As for the nature of the reagent, I'd call it [Ag(NH₃)₂]⁺! Physchim62 (talk) 01:02, 15 February 2009 (UTC)[reply]

You don't need NaOH at all. The reagent works well with ammonia alone. But if you use NaOH, be careful not to get the pH too high. In such cases, Tollens' reagent gives false-positive results (with glycerol, e.g.). --FK1954 (talk) 11:29, 11 October 2010 (UTC)[reply]

Photo[edit]

This page would really benefit from a photograph - the characteristic mirror is far better in an image than as a description. If someone replies with "be bold", I haven't got any access to Tollens' myself :) —Preceding unsigned comment added by 82.46.19.84 (talk) 18:13, 14 April 2010 (UTC)[reply]

Reaction mechanism requested[edit]

A full arrow-pushing mechanism, involving H₂O molecules, protonation etc. from the start of the reaction to finish would be very helpful. I can't seem to easily find any information on the exact reaction mechanism on the web though. Zynwyx (talk) 22:05, 22 January 2011 (UTC)[reply]

Version in other languages[edit]

Hi, This page seems to be the same in other languages. I just ended up there for the German version, but there is no link to an english version. https://de.wikipedia.org/wiki/Tollensprobe Well, the title of the English page refers to the reagent, while the title of the German page to the test reaction, but this is not really a reason to separate it? — Preceding unsigned comment added by 134.36.250.95 (talk) 16:03, 22 October 2018 (UTC)[reply]

redirect from other names[edit]

This reaction is known as "silver mirror reaction." Also, Chinese Wikipedia has two articles named "Silver mirror reaction(銀鏡反應)" and Tollens' reagent(多伦试剂)." However, the topic of silver mirror reaction is totally in the "Tollens' reagent," and the article named "silver mirror reaction" does not exist in English Wikipedia. It will be needed to redirect "silver mirror reaction" to "Tollens' reagent." 192.184.221.66 (talk) 06:11, 15 July 2023 (UTC)[reply]