User:Keith T. E. Bhumivarn/sandbox

Sliver mirror

    Silver mirror is the mirror with a thin layer of silver on a surface, which occurs as a result of the oxidation and reduction reaction between Ammonia and Tollence's reagent. It is the original experiment which demonstrates various chemical reactions and can be chemically prepared and accomplished in a laboratory with a high prudence and safety. Besides from that, the product from this experiment can be utilized tremendously as a practical lesson in Chemistry.  

Main Ingredients

    In this reaction, 
      Silver nitrate, AgNO3 
      Potassium hydroxide, KOH
      Dextrose or Glucose, C6H12O6 	
      Ammonia, NH3 
      Nitric acid, HNO3 

Procedures

    Firstly, sucking up Silver Nitrate (AgNO3) solution by using Pipette and let it flow down into a beaker.Then, dropping Ammonia (NH3) continuously into the beaker and concurrently swirling the beaker until the brown precipitate will emerge. Once this precipitate is noticeable, continue adding Ammonia until this brown solid disappears and the solution is full of the complex ion, [Ag(NH3)2]+ (aq), which can be observed by the clearness and colourless of the solution. After that, add the Potassium Hydroxide (KOH) solution into the beaker. The Silver(I) Oxide ion will precipitate and causes the dark brown solution. As soon as that circumstance occurs, continue adding Ammonia solution until the colour of the solution disappears. Then, pouring the consequent solution into a florence flask and add Glucose(C6H12O6) or Dextrose to a solution. Attaching the flask with a stopper and start swirling it in order to let every inch of surface exposes to the solution. Once the solution turns brown. Continue swirling again until the mirror forms. When a layer of Silver forms on a surface adequately, rinse the flask with a distilled water and discard the washing down the sink.

Overall Reaction

    When Nitrate ions from Silver Nitrate solution react with an Aldehyde group  in a basic aqueous solution like Potassium Hydroxide, the Aldehyde group will commence oxidizing complex ions into a metal. Those metals will accumulate and form a thin flim on an inner surface of the flask. 

      The overall reaction is as the following:

        CH2OH(CHOH)4CHO(aq) + 2[Ag(NH3)2]+(aq) + 3OH-(aq) → 2Ag(s) + CH2OH(CHOH)4COO-(aq) + 4NH3(aq) + 2H2O(l)

 Dextrose which contains the functional group like Aldehyde (-CHO) will act as a reducing agent and modify to be an acid (-COO), likewise;  the Sliver in the complex ion named Diaminesliver (I) will become a metallic metal by being an oxidizing agent. Those Silver will accumulate and form a thin film on an inner surface of the flask. In order to maximize the quality of Silver film, the flask with a circle shape in the bottom part like Florence flask will be mostly used. Since the main components in this reaction is Aldehyde group, any other compounds with Aldehyde group can also proceed this reaction.	

 Since this reaction will be most effective when it occurs in a water-soluble compound, the sugars like Dextrose or Glucose are principally combined with water in this experiment. Notwithstanding, Due to the difference of the number of Carbon and water molecule between the Monosaccharide like Dextrose and Disaccharide such as Sucrose, which is C=6, H2O=6 and C=12, H2O=11 respectively, their test result in Tollen's test- i.e. testing the ability to reduce [Ag(NH3)2+] to a metallic silver- are distinctive.While Dextrose gets a positive result, Sucrose receives a negative result. Thus, Dextrose is called reducing sugar whereas the sucrose is not.
    

Dangerousness and Safety

"Tollence's reagent" "Sliver Nitrate" "Potassium Hydroxide" "Ammonia" "Glucose"

    Despite the conspicuous result after finishing the experiment, it comprises a number of risks that participants must be aware. Firstly, the Tollence's Reagent which is received from the reaction between the compounds of Silver Nitrate and Ammonia and Potassium Hydroxide can feasibly explode and devastate anything around it when it is left for a long time. Thus, this substance should be promptly used after the synthesis of this solution.	
    The toxicity of each solution in this experiment is so severe that it can create a lethal injury, so participants must wear protector like googles and disposable Nitrile gloves every time the experiment has proceeded.

Application

      TBC. Learn about various reaction	
        - Precipitation
        - Redox reaction

Because this process of plating a flask with silver is performed without an external electrochemical circuit, it is called electroless plating. It is most often used to produce a metal coating on a surface that does not conduct electricity.