Turn on thread page Beta
    • Thread Starter
    Offline

    0
    ReputationRep:
    Hi, just wondering if I could get some help with these two questions:

    Why do ketones not yield a sliver mirror in the Silver Mirror Test?

    Why is HNO3 suitable for removing the silver mirror?
    Offline

    3
    ReputationRep:
    (Original post by gm18)
    Hi, just wondering if I could get some help with these two questions:

    Why do ketones not yield a sliver mirror in the Silver Mirror Test?

    Why is HNO3 suitable for removing the silver mirror?

    What is the reagent in the Silver Mirror Test?
    Spoiler:
    Show
    Tollen's Reagent: [Ag(NH3)2]+

    The silver mirror, is simply a deposit of silver. You are forming silver atoms which, by definition has an oxidation state of 0.

    Look at the oxidation state of silver in the reagent.
    Spoiler:
    Show
    It is +1.

    So when you form the silver mirror, you're actually reducing it.

    Therefore, the other reactant must be being oxidised.
    Spoiler:
    Show
    A + B ---> C + D. A is being reduced (gain electrons/gain hydrogen). It gains electrons if B is oxidised (lose electrons/lose hydrogen).

    Aldehydes readily oxidise (to carboxylic acids), but ketones do not. They do not have a hydrogen attached to the carbonyl group. That's why they don't form a silver mirror.
    • Thread Starter
    Offline

    0
    ReputationRep:
    thank you! so then why is HNO3 suitable for removing the silver mirror?
 
 
 

University open days

  1. Loughborough University
    General Open Day Undergraduate
    Fri, 21 Sep '18
  2. University of Cambridge
    Churchill College Undergraduate
    Fri, 21 Sep '18
  3. Richmond, The American International University in London
    Undergraduate Open Day Undergraduate
    Fri, 21 Sep '18
Poll
Which accompaniment is best?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.