Monday, July 11, 2011

Metal Lab Report- Silver





History:

The chemical symbol Ag comes from the Latin word “argentum” which means silver, and the root *arg- meaning “white or shining”. Silver is first referenced in the book of Genesis. Recorded infection prevention through use of silver dates back to Greece and Rome, but was rediscovered in the Middle Ages. During that time its use was to disinfect water and food during storage, and treating burns and wounds. In the 1930’s, silver iodide was used in babies’ eyes when born to prevent blinding as a result of bacterial contamination. It was considered extremely sacred and because of this, had extremely limited use. Due to its increased level of malleability and ductility it was used to create ornaments, utensils, and for paying debts, as well as personal and religious decoration. In 1792, silver played an important role in the United States monetary system when the silver dollar was issued by Congress. It was used as the nation’s money until discontinued in 1965. The people of the Ancient world also associated this metal with the moon. Since it has always been held high in value, gifts of silver jewelry were given as a symbol of trust, truth, excellence, wisdom, and love in many cultures. By looking at evidence found on islands in the Aegean Sea, the practice of separating silver dates back as far as 3000 BC. By 5000 BC, the method of separating the silver from the lead was already known. Silver was abundant all over Europe and West Asia, but the main inconvenience was that it was bonded to lead, which was very poisonous. By oxidizing this mixture, it was possible to acquire the valuable metals. The men who were mining the silver were also getting lead poisoning, so they died within two or three years. Silver is a great conductor of heat and electricity and is used in large amount for electrical applications.

Cycle production:

·      Preparing the ore
o   The metal is crushed into small pieces to make the material porous
o    It is oxidized so that it is not combined with any sulfide
o   A leach pile is created through:
§  Crushing the ore
§  Adding cement
§  Mixing
§  Adding water
§  Curing for 24-48 hours
·      Adding the cyanide solution and curing
o   Add a solution of water and sodium cyanide to the ore
§  Sprinkler systems
§  Ditches
§  Injection
·      Recovering the silver
o   Merrill-Crowe precipitation
§  Uses zinc dust to precipitate metal from the solution
§  The precipitate is then melted off and made into bars
o   Carbon absorption
§  Solutions are pumped through tanks containing activated carbon, added to the sodium sulfide solution, forms silver precipitate.

Uses:

·      Photography
o   Light sensitive salts, or halides, which are fundamental for developing high-quality photography
·      Electronics
o   High conductivity level
·      Switch and relay contacts
o    Automobile controls and accessories
·      Automotive window heating
·      Electrodes for electrocardiograms
·      Production of adhesives
·       Dinnerware
·      Mylar recording tape
·      Silver is the most reflective of all metals
o   Used to coat glass in mirrors
·       Used in x-ray vacuum tubes
·      Material for bearings



Abundance:

·      The largest silver producing countries are:
o   Mexico
o   Peru
o   United States
o   Australia
o   Chile

Other information:

·      Chemical symbol: Ag
·      Number of
o   Protons: 47
o   Neutrons: 61
o   Electrons: 47
·      Atomic Weight: 107.868 (108)
·      Atomic number: 47
·      Where it is found in the earth:  crust









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