EXPERIMENT 24-25 General Qualitative Unknown INTRODUCTION Qualitative tests for

Question

EXPERIMENT 24-25 General Qualitative Unknown INTRODUCTION Qualitative tests for 18 cations in Groups I-v were performed in experiments 4, 12-13, 14-15, and 19-20. The general qualitative unknown will contain a maximum of nine cations. Before the first lab period befor, your instructor will designate the nine cations to which your unknown will be limited, and these should be recorded in the data table on page 196. Before the first labperiod you will construct a chart on to separate and identify the nine cation In the flow chart, only the reagents (or reaction conditions) that are necessary to separate and confirm the presence absence) of list of cations. may use your prepare the the construction of the flow chart, omit all unnecessary steps, but be sure to include vital steps. Do not include details such as drops, volumes, decant, or centrifuge. Two laboratory be provided to complete the experimental work. You may use your the chart, your lab periods will analysis reports to perform manual, and all of your previous experimental separations and identifications. Your lab report will be due at the conclusion of the second laboratory period.

Explanation / Answer

Separation of cations

1. Add 6M HCl to the mixture. Precipitate forms. Filter

Precipitate of AgCl and PbCl2 forms. When heated precipitate of PbCl2 dissolves. AgCl remained solid.

2. To the fitrate from 1. was passed H2S. Precipitate forms. Filter

Precipitate of CuS (black), Bi2S3 (brown), SnS2 (yellow) forms

3. To the filtrate from 2. was boiled and basified with NH4OH. Precipitate forms. Filter

Precipitate of ZnS (white) and Al(OH)3 white forms.

When solution was made slightly acidic, Al(OH)3 dissolved. ZnS remained insoluble.

4. To the filtrate from 3. was added (NH4)2CO3. Precipitate forms. Filter

Precipitate of MgCO3 (white) forms.

5. The filtrate from 4. contains Na+ ion.

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