Differentiating Cations and Anions Through Characteristics and Logic

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Differentiating Cations and Anions Through Characteristics and Logic CHEM 111-499 John Bronold Introduction It is common for scientists today to use experimental troubleshooting methods to determine the cause of deficiencies in certain products. This process can be known as qualitative analysis. To practice qualitative analysis, a series of tests were conducted on standard solutions of different cations and anions involving precipitate formation and dissipation. Logic trees based on the results of these tests were constructed to later be used in the determining of an unknown ionic compound. Materials and Methods Part 1 – Cation Tests Potassium, iron (III), zinc (II), copper (II), and cobalt (II) cation solutions were made subject to two elimination tests involving the addition of sodium hydroxide in one and ammonium hydroxide in the other. Approximately 10 drops of each cation solution were placed in 10 different centrifuge tubes. To begin the sodium hydroxide test, 6M NaOH solution was added to one sample of each cation solution until either a precipitate was formed or until 20 drops were added. An additional 10 drops of 6M NaOH was added to each solution in which a precipitate formed and the solutions were shaken lightly to aid in the mixing of the reaction. To begin the ammonium hydroxide test, 15M NH4OH was added to one sample of each cation solution until the formation of a precipitate was observed, with care not to exceed 20 drops. 10 additional drops were added to solutions which formed a precipitate. In order to conduct the cation confirmation tests a Bunsen burner was connected to the desktop gas jet and lit with a striker. A nichrome wire loop was submerged in HCl then placed over the burner flame until no visible color change in the flame was evident. This was repeated after each individual confirmation test to remove any

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