Question

I need help figuring out the flowchart and if I have the right answers for the prelab please and thank you!

Group I, the Chloride Group BACKGROUND The precipitating reagent for the chloride group is chloride ion in an acidic solution. Only three of the 18 metal ions form a precipitate with this reagent: silver ion (Ag'), mercury(I)ion (Hg). and lead ion (Pb). Since lead chloride is somewhat soluble, it is not completely precipitated here, and a low concentration of lead ion appears also in Group II. We will be using silver and lead in Group I. Procedure Before starting analysis, complete the Chloride group flowchart Note: You may experience some difficulty in identifying the ions in your unknown, or you may be uncertain about whether a quantity of precipitate indicates that an ion is present or not. A side- by-side comparison of tests with a solution known to contain the suspected ion will be very helpful in such cases Precipitation Reactions of Group I Ag+ (aq) + Cl(aq) AgCl (s, white) Pb?" (aq) + Cl(aq) = PbCl: (s, white) Group 1: The Chloride Group Add 3 drops of 6 M HCI to 3 mL of the test solution, and mix thoroughly by stirring the mixture with a glass stirring rod. Centrifuge, decant the centrifugate (solution), and test for completeness of precipitation by adding 1 to 2 more drops of 6 M HCL If no more precipitate forms, precipitation is complete and the liquid (S1) may be discarded if only Group lions are possible in this unknown. If the unknown possibly contains ions from groups II-IV, SI must be saved. In this case, stopper and label the test tube containing SI for later analysis. Wash the residue (RI) with 1 to 3 mL of distilled water from your wash bottle, stir, centrifuge, decant, and discard the wash liquid. The residue Rl is now ready for further analysis of the ions in Group L. If no residue forms upon addition of 6 M HCl, neither Age or Pb ions in Group I is present and further analysis of Group I is unnecessary. Test for Lead Ion PbCl2 (s) +heat=Pb (aq) + 2 CH(aq) Pb+ (aq) + Cr2O2 (aq) = PbCrO. (s, yellow) Add 3 to 4 mL of distilled water to residue Rl and heat the mixture to near boiling while stirring Centrifuge the mixture and decant the solution (S2). Wash the remaining residue (R2) with 10 ml. of boiling distilled water in portions, centrifuge, and discard these washings. The washines from this precipitation must be discarded in a container labeled qualitative analysis solutions Add severnl drops of I M KCHOto the centrifugale (S2). A yellow precipitate confirms the presence of Pb2 If the unkome test tube com ash bottle. with 1 to 3 mL of distillo w ready for further analysis is present and further

Answer 1

Please follow the flow chart.

Solution of ions PHỤ R1-Residues. As ek 51-Solution to be discarded, if only group is possible. Otherwise use the solution for Groupil Wash with water. Boil.ceative Rewart with boiling water solution. Add drops of 1.0 M KCRO. To the sidud a loob of Water Csatrits, Decant. Yellow precipitate, if found | 55-சேN uts URTI , I Pb is present To the clear solution, Add 6 MHNO, doopwiss White precipitate-Ag is present

Prelab questions:

1. Yes you are correct. AgCl is less soluble than PbCl2, because of the lower Ksp of AgCl. Remember, the group analysis is based on the differences between Ksp.

2. When NH3 is added to R2, Pb+ is retained in the precipitate. Some of the Pb+ may form colloid [in the form of Pb(OH)Cl], but that has to be centrifuged and brought along with residue. The remaining solution contains Ag+ ions.

3. Ok

4. No. Please correct that. S1 must be saved. Please the detailed procedure once again. Especially, 4, 5, 6 lines under the heading Group I: The Chloride group