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Calling AP chem students

mvseniormvsenior Registered User Posts: 121 Junior Member
edited September 2007 in AP Tests Preparation
When NH3 is added to solid Hg2Cl2, some of the mercury ions are oxidized and some are reduced. A reaction where the same substance is both oxidized and reduced is called a disproportionation reaction. Write equations for each of these half reactions

When Fe3+ and Cu2+ react with NH3 solution they form two different types of products. One is precipitate and one complex ion. Write equation for half reactions.

How do u do it?
Post edited by mvsenior on

Replies to: Calling AP chem students

  • wxmannwxmann Registered User Posts: 855 Member
    For the first one, you should have your standard reduction potentials. That will make it easy. The cation is Hg2 2+ (ox. state of Hg +1). It oxidizes to 2Hg2+ (ox. state of Hg +2) and reduces to elemental mercury (ox. state of Hg 0).

    For the second one, do you know complexation rules? You'll need to know those (basically, the number of ligands, in this case ammonia, will be double the charge number of the original cation). Actually Fe3+ forms a precipiate when it complexes with NH3 for reasons I have no idea about; I found this out when I was playing around with my teacher's chemicals. I was always told that all complex ions are soluble so don't know why that doesn't.
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