Predicting an Unknown from Logic Trees

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Predicting an Unknown from Logic Trees Project 2 Report Ashley Garcia* Ayland Smith Introduction The purpose of the project was to use elimination and confirmation tests on several anions and cations to form a logic tree. Cations used in part 1 are potassium, iron (III), zinc (II), copper (II) and cobalt (II), and the anions in part 2 are chloride, carbonate, nitrate, and sulfate. The unknown contains both a cation and an anion. The logic trees from part 1 and part 2 were then used to identify an unknown. Materials and Methods Part 1 For the cation elimination test first 10 drops of potassium, iron (III), zinc (II), copper (II), and cobalt (II) were added to 5 centrifuge tubes and the color was recorded. Then for the metal hydroxide test, 6 M NaOH was added drop wise till a precipitate was formed. Each solution except potassium formed a precipitate, so then 10 additional drops of NaOH were added to the remaining solutions. Tubes were cleaned with distilled water and 6 M HCL. Next was the ammonia test 10 drops of each metal solution were added to new centrifuge tubes and 15 M NH4OH was added until the solution changed color or a precipitate was formed. 10 additional drops of 15 M NH4OH were added and changes were recorded. For the confirmation flame test 20 drops of the metal solutions were added to centrifuge tubes. A Bunsen burner was set up using a striker to lite the flame, and a Nichrome loop was dipped in 10 mL of HCL and placed in the flame till no color was observed. Then the Nichrome loop was dipped in each tube of metal solution, (dipping the loop into HCL and in the flame after each solution) and placed in the flame and color was observed for each metal solution. The test was repeated for each metal looking through cobalt glass. Materials and Methods Part 2 For the anion elimination tests 4 centrifuge tubes were obtained and 10 drops

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