Potassium Nitrate Lab Report

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Identifying the Unknown Ionic Compound as Potassium Nitrate
Arisbeth Carrillo*, Colette Harris, Nydia Garcia, Hannah Carroll, and Ratnamala Mandal
The identification of unknown compounds is useful in real world issues because it allows scientists to determine the culprit in cases like food contamination or water pollution which cause harm to a large population. The project conducted was broken down into three parts, forming a cation logic tree, forming an anion logic tree, and finally identifying an unknown compound, which in this case proved to be potassium nitrate. The logic trees were generated using the elimination and confirmation tests as well as observations for both anions and cations to determine the cation and anions
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This data generated the first question on the anion logic tree and two branches emerged between the anions that formed a precipitate and those that did not. After, 6 M HNO3 was added to the anions that formed precipitate, chloride and carbonate, the precipitate still remained for the anion chloride. This step provided another question for the anions that formed precipitates with AgNO3 and still had a precipitate after adding HNO3 and it generated two more …show more content…
First, chloride was tested by acidifying the ten drops sample with 6 M HNO3, adding five drops of 0.1 M AgNO3 solution and centrifuging the sample. Then four drops of 6 M NH4OH was added to the cloudy precipitate causing the precipitate to dissolve, but with the addition of 6 M HNO3 the cloudy precipitate reformed proving that the sample did contain chloride. This data enabled the confirmation test for the chloride anion. The confirmation test for sulfate was conducted by adding ten drops of the sulfate solution to several drops of 6 M HNO3 to acidify the sample then adding 0.1 M BaCl2 dropwise to form a precipitate. This lead to the confirmation of identity of sulfate on the logic tree. The confirmation test for nitrate was performed by mixing ten drops of the anion with several drops of 6 M NaOH and adding a few granules of zinc. The tube was then placed into a water bath until the solution turned the red litmus paper blue meaning the solution was basic. This allowed the confirmation of nitrate on the logic tree. The confirmation test for carbonate was carried out by adding 20 mg of the sample to the tube along with three drops of 6 M H2SO4. Then a drop of Ba(OH)2 was hovered over the solution which caused the drop to fizz and become opaque in color. This unique confirmation test assisted in completing the logic tree and verifying the identity of

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