Lab 7 Qualitative Analysis

Lab 7 Qualitative Analysis - Qualitative Analysis- Lab 7...

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Qualitative Analysis- Lab 7 Author: Holly Polk Lab Partners: Jim Hernandez, Vanessa Jordan, and Dominic Pisciotta Instructor: Yisheng Xu Chemistry Lab 151, Section 001 Date Work Performed: March 24, 2008 Date Report Submitted: March 24, 2008 Abstract: In this experiment, we performed a series of spot tests on a select set of cations, determined which cations and anions form precipitate and which do not, separated ions using precipitation and centrifugation, and used an analysis scheme to identify cations in an unknown sample. In the first test to measure the effectiveness of the analysis scheme, our analysis scheme correctly confirmed that the sample contained Potassium, Cobalt and Copper. We used our analysis scheme to test the unknown sample of Rosemont Ranch Ore and found that it contained nickel, copper, and cobalt.
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Introduction This experiment uses qualitative analysis to look at properties and compare them to known quantities in order to determine chemical composition. This experiment looks for certain cations in a sample using two basic chemical principles: Every cation has its own unique set of properties, and all compounds have some properties in common with other compounds. In order to find specific cations in a sample, separations will be performed. A reaction is run on the sample so that all cations with a certain property will be separated from a sample. Many reactions can be run in an analysis scheme to identify cations in an unknown sample. The procedure for the experiment includes making a 0.1 M solution from a salt, performing a series of spot tests on a select set of cations, determining which cations and anions form precipitate and which do not, separating ions using precipitation and centrifugation, and using an analysis scheme to identify cations in an unknown sample. There are 68 naturally occurring metals, and every one makes at least one cation. Some of them make more than one cation, but all have a unique set of properties. However, some of those properties may be similar. Most metals exist as cations either dissolved in the oceans, or in minerals as oxides and salts. Cations react with anions to make salts connected with very strong ionic bonds. The easiest way to separate those bonds is through precipitation. For a precipitate to form, the attraction between the ions and the water must be overcome by the attraction of the cations and the anions for each other. If the cations and anions that form precipitates are known, then the anions may be used to separate cations.
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Part 1 Test 1 Ion Results Ca2+ Ni2+ K+ Cu2+ Fe3+ Al3+ Ba2+ Co2+ PO4 3- precipita te precipita te x precipita te precipita te precipita te Milky White, some precipitate Purple, some solid NO3- clear clear x clear clear clear clear pink, no solid SO4 2- clear clear x clear clear clear Thick white, precipitate pink, no solid Cl- clear clear x clear clear clear
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Lab 7 Qualitative Analysis - Qualitative Analysis- Lab 7...

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