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Experiment 1: Qualitative Analysis

2 Materials and Methods: For the purpose of this experiment 4 unknowns A, B, C and D, provided by the University of Winnipeg, were collected and 4 test tubes were collected, cleaned with distilled water and labelled A, B, C and D for the respective salts. The test tubes were also cleaned in between experiments in order to avoid any cross- contamination. In order to mix the solutions, a stirring rod or a “finger vortex” method was used. The unknown sample C, which was white and powdery was obtained in a small vial labelled 40C in order have clear distinction from the three other salts. The preliminary tests were performed in order to narrow down the possibility of the ions in the unknown salt C and gather more information about the salt. The first solubility test conducted involved testing for solubility and the potential hydrogen (pH). A small amount of salt was added to 1mL distilled water in order to determine the solubility and pH. The inability of unknown C to dissolve in white indicated about the unknown being insoluble. The insolubility led to the solution being a white solution with white salt remaining unchanged in water. In order to determine pH, a pH strip was used, which was dipped in the salt solution. The resultant strip was compared to a pH strip test for the distilled water and the pH of the solution containing the unknown relative to distilled water was determined to be basic. The second preliminary test involved adding 1-2 drops of H2SO4, provided by the University of Winnipeg to a solution containing a small amount of the unknown salt C and about 1mL distilled water. The test was used to determine the solubility in H2SO4 and evolution of gas, where it remained insoluble and produced a colourless gas, with bubbles. The production of gas in an unknown salt with H2SO4 is also an indication for a carbonate anion being present in the salt.

3 After the preliminary tests, specific ion tests were conducted to determine the identity of the specific ions in the salt. For the insoluble salt, a small amount of BaCl2 was added to the solution and production of any gas, which was produced in case of unknown C was an indication of CO32- anion in the salt. Next, group I and II test Cation test was performed on the unknown salt C, where a solution of the salt was prepared and a few drops of 3M NaOH were added to it, and absence of hydroxide as in this case was the indication of group II element. A flame test was then performed to determine the cation present in the salt, for which a Nichrome wire was cleaned by dipping in 12M HCl and heating in the hottest part of the flame. The clean wire was then dipped into the vial containing unknown C, which was also heated in the hottest part of the flame. The immediate colour of the flame was observed to be greenyellow, which gave indication about the Ba2+ ion being present in the salt. Discussion: Different elements in different groups have very distinct characteristics that differentiate they and give them a unique identity. For the purpose of this lab, these unique chemical characteristics helped in determining the identity of unknown salt C. The preliminary tests helped narrow down the results to a possible list of ions that the salt could contain. The first preliminary test involved testing for solubility and pH of the salt in distilled water. Unknown salt C had a pH greater than the pH of distilled water in the pH strip test. Since the pH of the salt indicated that the salt was basic, it helped eliminate possibility of any acidic ions in the salt. The solubility of the salt in H2SO4 helped identify behaviour of the cation, and gas formation provided indication about the anion in the salt.

4 The salt was determined to be basic, hence the consideration of doing an ammonium test was eliminated. The production of gas in the H2SO4 test aided in determining that a carbonate test would be suitable to be performed because of the soluble nature and gas production of the salt C with H2SO4. The production of gas in the carbonate test indicated the presence of CO32and absence of PO43- and SO42- in the salt. The salt was then tested for the possible cations, where group I and II cation test was performed. The group I and II ions are neutral in nature and would be basic with the possible CO32- anion. The presence of a hydroxide salt in this test indicated the presence of group II cations and the absence indicated the presence of group I cations. The reaction of the unknown sample C with 3M NaOH provided by The University of Winnipeg indicated the presence of group II cation. Finally, in order to determine the possible identity of the cation in unknown salt C, a flame test was performed. The flame produced by the Nichrome wire when dipped in salt C produced a green- yellow flame when heated, thus indicating the possibility of a Ba2+ ion being present in the unknown. Further research was conducted in order to determine the validity of the tests and the results obtained. BaCO3 was an insoluble salt, with this being known the reaction of Ba2= with Na2CO3 was searched, and was determined to produce an insoluble white solid salt1. Research indicated the formation of a green- yellow flame in a flame test2, similar to colour determined in the lab. The carbonate test for BaCO3 was conducted where H2SO4 was added, and it is determined from the research and the experiment that the reaction produced BaSO4, CO2 and H2O3. BaSO4 which appeared as a precipitate was because of its insoluble nature in H2O and CO2 was the gas determined in the experiment.

5 There were several factors that could affect the results for the experiment. Even though efforts were made to avoid any contamination, the inability to properly clean the test tubes with distilled water might have affected the results. The chemicals and the standards provided were shared by all the students and could have acted as a source of cross contamination that could affect the observations made in the experiment. The amount of distilled water or the salt used, was not consistent over the different results, and only an approximate amount was used, this means that the concentration of the solution was not consistent for each of the tests, which might have affected the results for various tests. For example, if a very little amount of an acidic salt was added to a large amount of water, the results might come up as acidic for a pH test or if too much salt was added to a little amount of water, the salt might remain undissolved, making it look like insoluble in water.

Appendix: Carbonate Test: BaCO3 (aq) + H2SO4(l)

BaSO4(s) + CO2(g) + H2O(l)

Phosphate and Sulfate Test: BaCO3 (aq) + 2HCl(aq)

BaCl2(aq) + CO2(g) + H2O(l)

The absence of a precipitate is a positive result for the presence of carbonate in BaCO3. Group I and II cation Test: BaCO3 (aq) + 2NaOH(l)

Ba(OH)2(s) + Na2CO3(aq)

The formation of precipitate is a positive result for the group II cations.

6 References: 1. Van Nostrand's Scientific Encyclopedia. Ninth Edition. Volumes 1-2. (March 26, 2003). Journal- American Chemical Society, 330, 3671. 2. Schumann, W. (1992). Minerals of the world. New York: Sterling Pub. Co. 3. Ropp, R. C. (2012). Encyclopedia of the Alkaline Earth Compounds. Amsterdam, Nederlands: Elsevier Science & Technology Books....