The Qualitative Analysis Of Cations Essay, Research Paper

Qualitative Analysis of

Cations

Introduction:

The purpose of this experiment is to demonstrate the separation and identification of metal ions based on the insolubility of certain salts. The solubility rules should be taken into account. If a solution dissolves in water, the result contains both cations and anions. Analyzing different ions to discover their nature is the main goal of this experiment. Separation of the cations by testing the differences in solubility of different metal salts is done. Also, identification of the metal ions is done by the flame test procedure and by the characteristic reaction procedure. Both of the separation and identification methods will be used. Separation procedure will be done by the methods of decanting or centrifuging.

Procedure:

Equipment-

10ml.Graduated cylinder

3 test tubes

Bunsen burner

Nicrome wire

Beaker

Evaporation dish

Blue cobalt glass.

Chemicals-

6M HCL

0.1M K2CrO4

1M HCL

1M NaOH

0.1M Na2CO3

0.1MNH4SCN

0.1K4[Fe(CN)6]

KSCN

DMG

Hazards-

HCl is currosive & toxic. It can cause burns

DMG, K4[Fe(CN)6, are irritants

Most of the solutions are poisonous and all should be treated as if they are.

A. Preparation

1.Obtain 6ml of the unknown solution. In a graduated cylinder.

2.Number each test tube.

3.Add 5 drops of the unknown solution into each of the test tubes.

B. Forming a Precipitate

1.Add approximately 3 drops of Na2CO3 solution to the solution in test tube one.

Thoroughly mix. If the solution turns into a white precipitate then it includes ions

from set 2. Record the result.

Waste Disposal- there should be waste bottles under the fume hood. Dispose of

solution in a labeled Na2CO3 mixture waste bottle.

2.In test tube two add 5 drops of 1M HCL to the unknown solution. Thoroughly mix.

If the solution turns to a white precipitate, it has ions from set 1 . If it turns to a yellowish/red precipitate, it has ions from set 2. Record the results.

Waste Disposal- discard in a labeled HCL mixture waste bottle.

3. In test tube three add approximately 3 drops of 1M NaOH. If the solution turns to a brown precipitate it has ions from set 1, if the solution has a white precipitate it has ions from set 2, if the solution has a blue,green, or red precipitate it has ions from set 3. Record Observations.

Waste Disposal - discard in a NaOH labeled mixture waste bottle.

C. Separation of Ions

1.To separate the ions decanting, should be used or a beral pipet.

2.The ions should be separated completely.

Waste disposal- place the remaining liquid in the appropriate labled waste container.

D. Chemical Test

1.If a precipitate forms proceed with the following steps.

2.In each test tube with a precipitate add 4-5 drops of K4[Fe(CN)6]. If the solution turns white it has Ag ion, if the solution turns yellow it has Ba & Ca ions, if the solution turns blue it has Fe ions, if the solution turns red it has Cu or Co ions. Record the result.

3.In the test tubes without reactions add 4-5 drops of K2CrO4 (keep in fume hood). If the solution turns red it has the Ag ion, & if the solution turns yellow it has the Pb ion.

4.Record the result.

5.Next add 4-5 drops of DMG to the solution without reactions. If the solution turns bright red then it has the Ca ion, if the solution turns pink it has the Ni ion. Record the result.

D. Flame Test

1.Dip the Nichrome wire into 6M HCL shake it around, not too vigorously, and rinse with distilled water.

2.Make a suitable flame with the bunsen burner. Dip the wire in the test tube with no reaction in the unknown solution.

3.Swipe it through the flame and use a Blue Cobalt glass to view the color. If the color is blue it has the Pb ion, if the color is green it has the Ba ion, if the color is yellowish/red, it has the Ca ion , if the color is bluish green then it has the Cu ion, if the color is red violet it has the Li ion, if the color is purple red it has the K ion. Record the observations.

4.Dip the wire in the 6M of HCL again when cool & rinse with distilled water.

Waste Disposal- the remainding solution should be placed in the appropriate containers.

Conclusion

The unknown solution is contains .

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