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Unknown Salt Essay

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The objective of the experiment was to identify the unknown salt that was given. The unknown salt contained an anion and a cation labelled, 38A. A series of preliminary tests were first conducted in order to help choose which confirmation tests should be used to identify the compound. The preliminary tests included pH and solubility, and the behaviour of the salts with concentrated sulfuric acid. The compound was found to have a slightly acidic pH, around 6.9 while being soluble in water. The compound showed no change in properties after the addition of concentrated sulfuric acid. The confirmation tests were then divided into two parts, one for the identification of the cation and the other for the identification of the anion.
The anion tests …show more content…

A solution of the salt was prepared and 4 drops of AgNO3 (10%) solution were added. This created an off-white creamy precipitate. In order to be sure that this was not a false positive, three drops of nitric acid (6 M) were added. As the precipitate did not dissolve this meant that the unknown anion had a halide. To confirm which halide it was, a fresh solution of the salt was created and acidified with a few drops of HNO3 (6M). This was accompanied by 1ml of chloroform, an organic solvent. The addition of a few drops of NaOCl solution, swirled gently as the drops made contact with the unknown created a brown-yellow …show more content…

The observation of chemical behaviours under specific conditions allowed for the use of process of elimination. Given the observations found in the materials and methods section and the data found in the lab manual1 it was found that the anion was not acetate or carbonate, but rather a halide, specifically Br due to the brown-yellow hue of the organic layer. The observations for the cation test along with the data from the lab manual1 showed that the unknown was from group II. Since the flame test showed no observable difference this allowed for the conclusion that the cation was Mg2+.
For the anion, the most difficult test was the acetate test as the test was concentration dependent and it also relied on colour as its identifier. This was difficult to achieve as the concentration was hard to keep constant, and the colour was difficult to pinpoint. Possible solutions include getting access to a Drypette TM, a manual powder pipette that would dispel a more accurate sample of salt. This would then make for a more reliable consideration of the color as an indicator of the presence of

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