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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: amarnath on December 17, 2004, 06:58:42 AM

Title: silver copper alloy and Nitric acid
Post by: amarnath on December 17, 2004, 06:58:42 AM

Hi all,

  can any experts here elaborate what happens when silver alloy made up of silver , copper treated with nitric acid .
   
   And can advice list of metals and or alloys like steel that is non reactive to conc and dil nitric acid or other inorganic acids

Title: Re:silver copper alloy and Nitric acid
Post by: AWK on December 17, 2004, 07:08:14 AM

Copper and silver will dissolve.

Al is resistant to action of concentrated HNO3

Title: Re:silver copper alloy and Nitric acid
Post by: amarnath on December 17, 2004, 09:03:57 AM

Hi AWK,

  Thanks for prompt reply. Is there is any way to separte silver metal alone from that acid mixture were silver copper alloy is allowed to react

Title: Re:silver copper alloy and Nitric acid
Post by: AWK on December 17, 2004, 10:55:50 AM

"Selective elution" of copper from alloy is rather difficult
Selective precipitation of silver from solution of salts is easy.

Title: Re:silver copper alloy and Nitric acid
Post by: amarnath on December 17, 2004, 11:13:37 AM

Hi AWk,

  Thanks again . Can you please elaborate what are regeants that can be used for selective precipitation of silver from that acid mixture ( i.e copper silver nitrate mixture i guess ) and after selective precipitation say silver nitrate to silver chloride by adding common salt can i make selective precipation ? and how can i get 99.99 % pure metal from that silver salts

Title: Re:silver copper alloy and Nitric acid
Post by: jdurg on December 17, 2004, 03:38:35 PM

Quote from: AWK on December 17, 2004, 07:08:14 AM

Copper and silver will dissolve.

Al is resistant to action of concentrated HNO3

Are you sure about this?  I know that aluminum will dissolve in plain old hydrochloric acid if it's given a bit of time, so I'd think that it would do the same in HNO3.

Title: Re:silver copper alloy and Nitric acid
Post by: kevins on December 19, 2004, 10:39:22 AM

amarnath,

I think you can use common salt to precipate the silver, wash the silver chloride with pure water. Mix the silver chloride with sodium carbonate and heat ( I am not sure the temperature, may be up to 700C). A sponge silver metal can be purifiy with electrolyisis.
Please try.

Title: Re:silver copper alloy and Nitric acid
Post by: AWK on December 20, 2004, 01:50:48 AM

Quote

Are you sure about this?  I know that aluminum will dissolve in plain old hydrochloric acid if it's given a bit of time, so I'd think that it would do the same in HNO3.

Pure Al, (even Zn) undergo passivation in concentration nitric(V) acid.
The concentrated nitric acid is transported by the railway transport and in automobile transport in the special tanks made of aluminium.

http://www.pc.chemie.uni-siegen.de/pci/versuche/english/v44-24-2.html

Title: Re:silver copper alloy and Nitric acid
Post by: amarnath on December 20, 2004, 05:42:24 AM

Hi kevins,

  Thanks for reply . In this case if i use common salt to make ppt of silver chloride while adding NACl to soln of silver nitrate and copper nitrate won't that copper nitrate too get ppt of copper chloride?

Title: Re:silver copper alloy and Nitric acid
Post by: amarnath on December 20, 2004, 05:45:13 AM

Quote from: kevins on December 19, 2004, 10:39:22 AM

amarnath,

I think you can use common salt to precipate the silver, wash the silver chloride with pure water. Mix the silver chloride with sodium carbonate and heat ( I am not sure the temperature, may be up to 700C). A sponge silver metal can be purifiy with electrolyisis.
Please try.

Also can you explain chemistry behind this process . what happens when silver chloride and sodium carbonate mixture is heated and why silver metal appears in metallic state . In this process Naco3 acts as reflux?

Title: Re:silver copper alloy and Nitric acid
Post by: kevins on December 20, 2004, 12:14:48 PM

Because of silver chloride is slightly soluble in nitric acid, neutralize the acid first and add sodium chloride solution to precipate the silver chloride. (Do not use the filter paper to separate the ppt because the glatinous silver chloride can not be removed easily on the surface of filter paper. I recommended to use the decant method or centrifuge method) Wash the ppt with pure water. Mixing the dry chloride with one-third of its weight of dry sodium carbonate and fusing the mixture at a bright red heat. The fused metal is then pouring into a mass of cold water.

In the "fusion" process, a sodium chloride ,silver oxide and carbon dioxide  is given out. At the high temperature, silver oxide is decomposed to give out metallic silver.

Please try. :)