Sunday, February 20, 2011

CHEMISTRY WORKING PROJECTS

  • GOLDEN RAIN
  • PHOSPHOROUS MOON
  • THE LEMON BATTERY
  • CHEMICAL GARDEN ( SILICA GARDEN )

                                                                  GOLDEN   RAIN
This experiment is based on an instantaneous chemical reaction known as “Gold Reaction”. The bright yellow precipitate is formed by mixing the solutions containing lead(II) ions and iodide ions.
Pb(NO3)2   +  2 KI    ------>      PbI2   +   2KNO3
HOW TO DO THIS ?
Two solutions need to be prepared in advance. These are 0.3 wt.% solutions of potassium iodide and lead nitrate. The solutions need to be made strictly in distilled water and make sure that both the solutions should be perfectly colourless before mixing.
Now mix  approximately equal volumes of KI and Pb(NO3)2 solutions in a flask and allow to settle. As a result of this, the lead iodide will precipitate out and get settled at the bottom of flask.
Now decant off the supernatant liquid ( mother liquior) and add the wet precipitate to a similar volume of hot water (70 – 80C) acidified with a little glacial acetic acid in a round bottomed flask. The precipitate will quickly dissolve.   
Now allow the solution to cool down.   After the flask is cooled (under a stream of cold water) beautiful shiny golden crystals begin to form; these slowly fill the flask. If the lamp is allowed to shine on the flask against a black background the crystallisation process appears to the viewers as “golden rain” in a blaze of beautiful      
Colour. The effect is even better if room is darkened.






                                 
                                     PHOSPHOROUS  MOON                                                                                                                                                                 
                                 Phosphorous is a very reactive element and unites oxygen with great rapidity.Yellow phosphorus burns in the oxygen to form white vapours of phosphorus pentoxide along with the production of large amount of energy.
HOW TO DO THIS ?
In order to make this experiment successful, you need to produce the energy at a rapid speed. so fill a large jar or a round bottom flask with pure oxygen and then light a piece of phosphorus and then seal its mouth.                               You can do as shown in the diagrams below.     
P4 + 10 O2 -> 2  P2O5
Due to this the white vapours of  phosphorous pentaoxide forms here  in the form of  smoke is very hot, so the smoke rises and is rather beautifully lit by the light given off by the flame.
Now the hot phosphorous pentaoxide smoke slowly buids up and cools down.Finally the smoke cools enough that the particles of phosphorous pentaoxide inside the flask makes the still warm air denser than the cold air below and starts sinking down.This sinking produces the beautiful tendrils as the smoke falls and the air rises to take its place.


                             













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