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Silver Mirror Experimental Note
May 24, 2017

Silver Mirror Silver mirror test Note vulgar. Waterproof mirror, mercury mirror, glass surface silver mirror, glass mirror, mirror glass, and so on. Silver mirror is widely used in furniture, handicrafts, decoration, bathroom mirrors, make-up mirrors, optical mirrors, and car mirrors

  Silver mirror, is a kind of glass mirror, mainly refers to the back of the reflective layer of silver glass mirror; ordinary civil decorative mirror is divided into aluminum glass mirror, and silver-plated glass mirror two. Mainly used for furniture, car mirrors, bathroom mirrors and so on. In the storage of the mirror, should not be stacked with alkaline and acidic substances together to avoid storage in a humid environment Silver mirror also refers to the reduction in sugar testing, reducing sugar and Torrance reagent reaction, in the test tube wall to generate elemental silver phenomenon

  Silver Mirror Add 1 mL of 2% AgNO3 solution to a clean tube and add 2 drops of 10% aqueous sodium hydroxide solution. Then, 2% dilute aqueous ammonia was added dropwise to the side of the tube until the initial precipitate was dissolved. Ammonia solution. And then dropping 3 drops of acetaldehyde or glucose solution, the oscillation after the test tube on the hot water in the water bath heating

  Silver Mirror Silver ions in the aqueous solution can provide empty orbit, can provide solitary electrons to the NH3 molecules to form a coordination bond, it will not form AgOH precipitation, the reaction equation is Ag + + 2NH3 = Ag (NH3) 2 +

  In this test, other reducible substances may be used instead of acetaldehyde, such as glucose (similar to acetaldehyde and also aldehyde groups). Formaldehyde (can be seen as having two aldehyde groups) is oxidized to ammonium carbonate (NH4) 2CO3. C6H12O6 + 2Ag (NH3) 2OH ---- → (water bath heating) C5H11O5COONH2 + 3NH3 + 2Ag ↓ + H2O glucose reaction formula to reflect the internal structure of glucose and broken bond conditions: CH2OH-CHOH-CHOH-CHOH-CHOH CHO + 2Ag (NH3) 2OH → (water bath heating) CH2OH-CHOH-CHOH-CHOH-CHOH-COONH2 + 2Ag ↓ + 3NH3 + H2O

  1. Test tube to be clean (this is one of the key to the success of the experiment). Otherwise, only get black loose silver precipitation, no silver mirror produced or produced by the silver mirror is not bright.

  2. After the solution is mixed, the oscillation should be sufficient (this is the key to the success of the experiment). Add the last solution, the oscillation should be fast, otherwise there will be dark spots or produce silver mirror uneven.

  3. Add the amount of ammonia to be appropriate (this is the key to the success of the experiment three). Ammonia concentration can not be too much, the rate of ammonia must be slow, otherwise ammonia is too easy. Excessive ammonia will reduce the sensitivity of the reagent, and easy to produce explosive substances Ag3N.

  4. Alkali can make acetaldehyde and silver ammonia solution at room temperature reaction, but if the drop of sodium hydroxide too much, the reaction rate is too fast, the resulting silver mirror will be black.

  5. Silver ammonia solution can only be temporary preparation, not long home. If the home for a long time to precipitate silver nitride, such as silver sulfide and other explosive precipitates. These precipitates that use the glass rod friction will break down and a violent explosion. Therefore, the experiment should be completed immediately after the waste tube in the tube, with dilute nitric acid dissolved on the wall of the silver mirror, and then rinse the tube with water.

  6. Ammonia concentration should not be too large, or easy to overdose, resulting in experimental failure. Ammonia concentration of 2% is appropriate.

  7. Acetaldehyde concentration, the reaction rate is fast, precipitation silver mirror fast, but prone to dark spots, plus [1] fast oscillation speed can avoid dark spots. A solution of ethanol to reduce the role of acetaldehyde concentration, making the reaction rate is moderate, easy to control. In the presence of ethanol, the resulting silver mirror is uniform and bright.