CHM 277 Final Lab Report

CHM 277 Final Lab Report - Finding the Composition of an...

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Finding the Composition of an Unknown Ionic Compound Paul Moses Chemistry 277D Instructor: Kalani Cox March 28, 2007
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Introduction The experiment presented is used to determine the makeup of an unknown ionic compound. The unknown used in this specific experiment was a solid that was soluble in water. A soluble compound dissociates into individual ions when placed in water. The goal was to individually identify the cation and anion in the compound. A cation is a positive ion in a reaction, and the anion is the negative ion. There were several tests used to do this. A double displacement reaction contains two compounds that switch cations in the reaction and can be used to identify the cation in an unknown. The flame test uses heat to identify certain cations, as many change color when heated. When heated, electrons become excited, which causes them to jump into higher shells. When they go back to ground state, these electrons release energy, which often falls into the visible light spectrum. These are the two primary cation tests. There are eight commonly used anion tests. Unless concentration is specified below, it is not important to the success of the test. The chloride test reacts a solution containing the unknown with 6M HNO 3 and .1M AgNO 3 . Should a precipitate form, chlorine is present in the unknown. The iodide test mixes a solution containing the unknown with CCl 4 and chlorine water. A purple color confirms the presence of iodide. The sulfate test mixes the unknown solution with 6M HCl and BaCl 2 solution. If a white precipitate forms, sulfate ions are present. The nitrate test only works in the absence of iodide. One must add the unknown solution to H 2 SO 4 . Once this has been stirred and
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This note was uploaded on 04/16/2008 for the course CHM 277 taught by Professor Cox during the Spring '07 term at Portland.

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CHM 277 Final Lab Report - Finding the Composition of an...

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