Qualitative Analysis Lab Report Sample

In 1860, the first instrumental analysis was performed by Robert Bunsen and Gustav Kirchoff who used flames tests that led to the discovery of the elements rubidium (Rb) and caesium (Cs). After this, this method was used everywhere to find the chemical make ups of many substances. For example, in 2007 there was a huge problem where tainted pet food would cause many pets to become ill. Qualitative analysis was used and it was discovered that Melamine was found in the pet food which altered the results of the protein tests, in which caused more ammonia to be generated. The spike in the ammonia level caused the illnesses. The purpose of this experiment was to determine a series of tests that qualitatively show what element is present in a compound.
Then 0.1 M AgNO3 was added until a precipitate formed with less than 5 drops. Then to each of the solutions that a precipitate formed, 6 M HNO3 was added to see whether or not the precipitate stayed. Then 10 drops of chloride solution was placed into a centrifuge tube. Then 10 drops of 6 M HNO3 was added. Then 5 drops of 0.1 M AgNO3 was added and the solution was centrifuged for 2 minutes. Then the supernatant was discarded. Then 4 drops of 6 M NH4OH was added to the precipitate. To solutions where the precipitate dissolved the sample was acidified with 6 M HNO3. If the precipitate reforms then it contains chloride. All observations were recorded. Next add 10 drops of sulfate solution to a new centrifuge tube and several drops of 6 M HNO3 solution was added until the solution turned acidic. Acidity was tested by using a stirring rod and litmus paper. BaCl2 was added until a precipitate formed. All observations were recorded. Then, 10 drops of nitrate solution and 10 drops of 6 M NaOH were mixed together in a centrifuge tube, then the mixture was transferred to a dry centrifuge tube with a pipet. A few granules of zinc was added to the centrifuge tube and it was heated for 2 minutes before the Zn started to break down and gas started to be emitted. A piece of red litmus paper was creased into a V and wetted and was placed into the top of the tube. The paper turned blue
Although this was the result of the experiment the compound could be CoCl2. The first sign was that the color of ZnCl2 is actually a white powder and not a red powder like the unknown compound. However, CoCl2 is a red powder and according to figure 1 it burns orange as well. It is believed that there was a misconception on whether or not a precipitate dissolved when excess 6M NaOH was added. If the precipitate did not actually dissolve then the logic tree would not lead towards zinc, but towards copper and cobalt. Then since the solution burned orange it would most likely be cobalt and not