Amalgam sample

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The amalgam sample is a preliminary test for mercury salts in analytical-inorganic chemistry . For this purpose, a nitric acid sample solution is placed on a copper sheet - what remains is a silvery amalgam stain that cannot be wiped off:

Redox reaction : mercury cations and elemental copper oxidize to copper cations and elemental mercury.

Instead of a nitric acid solution, hydrochloric acid and sodium chlorate can also be added to the solid sample.

The mercury forms an alloy with the copper sheet , the copper amalgam . This is initially gray and becomes shiny silver when rubbed.

Silver, mercury and a sample that does not contain either on a 5 cents coin that has been cleanly etched with HCl.
Metal mirror on a 5 cents coin. If it is mercury, it will sublime in the Bunsen burner flame.
A mirror of mercury hums up in the Bunsen burner flame.

If silver is present in the sample, it is also deposited. To distinguish it, you can heat the piece of copper so that the mercury evaporates and is deposited on a watch glass held nearby. The droplets can then be seen with a microscope.

literature

  • Jander-Blasius: Introduction to the inorganic-chemical internship , 14th edition, S. Hirzel Verlag, Stuttgart, 1995, ISBN 3-7776-0672-3

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