Lab 3 Redox Arena Lab Answers

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Kumari Biswas Chem 106 – 07 October 06, 2014 Menglu Shi Group member: Shemeika McLaren, Jose Suarez, Colleen Shum Lab 3: Redox Arena Redox Arena Lab Part I Observations and Data Observations of starting materials and standards Chemicals | Observations | The Four standards | Granular zinc | Silver-gray irregular solids | Iodine crystals | Purple-black spherical solids, strong smell | Zinc ion and iodine-iodide-triiodide ion in H2O | Red brown liquid | Zinc iodide | Gray white solid powder | Chemicals used for tests | 0.17 M acetic acid | Clear liquid | Mineral oil | Thick clear liquid | Silver nitrate (AgNO3) | Clear liquid | Magnesium turnings | Solid curled metals | 3 M HCl | Clear liquid | Other chemicals…show more content…
Through our identification tests, we identified the gray solid to be zinc granules, the colored solution to be zinc ion and iodine-iodide-triiodide ion in water and the white solid to be solid zinc iodide. These identifications compared well with two other groups data. Ismat Zerin and Savita’s group also identified these substances to also be zinc granule, zinc ion and iodine-iodide-triiodide ion in water, and zinc iodide. Even though our conclusion was the same, our identification results did differ to some extent. For the identification test for the gray solid, we all concluded that this substance showed negative results for every chemical tested except for the zinc metal. In other words, this gray solid only significantly reacted with HCl, indicating the presence of zinc metal. However, our test for the iodide ion with the gray solid, where we added AgNO3 to the gray solid, was very unclear as we did see a yellow liquid, which we could not decide whether it was a precipitate of AgI. Other substances produced a clear precipitate but this one did not. So we concluded that this Zinc did not contain significant amounts of iodide ion. There might have been slight amounts of iodide ion from the gray solids not being washed properly after it was isolated from the zinc iodine solution (the colorless solution after the completion of the reaction). Next time, we would need to wash the zinc granules more vigorously, to clearly identify that there is no AgI precipitation to indicate the presence of iodide

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