Qualitotive Analysis of Selected Anions The weak acid phosphoric acid stays in s

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Qualitotive Analysis of Selected Anions The weak acid phosphoric acid stays in solution largely as molecules. Notice that these reactions are both double replacements. The chlorine water test, on the other hand, relies upon a single replacement reaction. All three of the halide ions behave similarly in both the silver nitrate test and the barium chloride test, but they behave differently in the chlorine water test. For example: Then extract the aqueous iodine into a nonpolar organie solvent (such as cyclohexane) where it takes on a characteristic intense purple color. Add 10 drops of the first known halide solution, 10 drops of the solvent provided, and 10 drops of chlorine water to a clean micro test tube. Stopper the test tube, and shake it energetically to mix the three liquids. Allow the aqueous and organic layers to settle out, and record your observations. Especially pay attention to the color of the organic layer. Dispose of the waste mixture in the proper labeled container. Repeat the same procedure with the other two known halide solutions and any unknown that you can't definitely identify by the silver nitrate and barium chloride tests Analytical strategy Identification of your unknown follows a process of matching and elimination. If, after performing t first silver nitrate test, you observe that your unknown had a color the same as one of the uniquely- anion precipitates, you need no further tests. If, on the other hand, your unknown anion solution gives a white precipitate in the silver nitrate test, you will need further tests to identify the unknown because several of the AgX compo unknown's behavior matches only one possible known anion. you have completed your analysis. One test could suffice, but you may need up to five tests. When you think you have identified both of your unknowns, get your instructor to verify your analysi and sign your data sheet. unds give white precipitates. When you can decide that the Qualitative Analys

Explanation / Answer

Here, 8 known solutions are given namely :-

(1) Sodium chloride (NaCl)

(2) Sodium bromide (NaBr)

(3) Sodium iodide (NaI)

(4) Sodium sulfate (Na2SO4)

(5) Sodium carbonate (Na2CO3)

(6) Sodium phosphate (Na3PO4)

(7) Sodium hydroxide (NaOH)

(8) Sodium acetate (CH3COONa)

In test 1 two unknown solutions are given.

You have to mix two drops of two unknown solution and two drops of each of the eight known solution as mentioned above with 0.1 M silver nitrate in all different wells (Two unknown + eight unknown = 10 wells). Then perform the test as mention in the preocedure.

In some wells precipitate will obtain, while in some precipitate wil not form. Then take those precipitate in the spot dish and dissolve in 1 M HNO3.

Now, the precipitates whose anions are the bases of weak acid will dissolve in 1 M nitric acid.

You have to record observation of all the ten wells. Now, you have to take this solution in a proper labelled container, so as to perform further the barium chloride test.

In test 2, you have to add 0.1 M BaCl2 in each of the ten wells of the spot plate. Then add eight known solution and two unknown solution to 2 drop barium chloride solution. and record your observation wheter they precipitate or not. Some will precipitate and some will not. Note down the color, texture capacity and other visible characteristics.

Then add 1 M hydrochloric acid to each well that contain insoluble barium compound. By adding hydrochloric acid, some will re-dissolve and some will not. record your observation.

Test 3

If you have identified the two unknown solution from these two test, then you dont have to perform test 3. Only perform chlorine water test if unknown solution contains halide ions.

The first two test rely on double replacement reaction and chlorine water test rely on single replacement reaction.

You have to find out the two unknown solution given to you and their rection towards above test (are they soluble or not), then mention your observation on the table provided.

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