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2. Because a qualitative analysis may often consist of a rather long series of manipulations, precipitations, centrifugations, and separations, flow charts are often prepared to summarize graphically the steps to be undertaken. For this analysis of Group I, prepare a simple flow chart showing what ions are present at each point in the procedure, what reagents are to be added, and the result to be expected at each point.

2. Because a qualitative analysis may often consist of a rather long series of manipulations, precipitations, centrifugations, and separations, flow charts are often prepared to summarize graphically the steps to be undertaken. For this analysis of Group I, prepare a simple flow chart showing what ions are present at each point in the procedure, what reagents are to be added, and the result to be expected at each point.

Chemistry
Chemistry
10th Edition
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Chapter1: Chemical Foundations
Section: Chapter Questions
Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...
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I need help with one of my pre-lab questions which I want to understand. Its question number 2, the one that highlighted. I don't want to make it over-complicated, I want something that I can understand.

# 15. Qualitative Analysis of the Group I Cations ## Objective A sample containing only the Group I cations will be analyzed for the presence of silver(I), mercury(I), and lead(II) ions. ## Introduction The Group I cations are those species that form chloride precipitates that are insoluble in acid. The group includes Ag⁺, Pb²⁺, and Hg₂²⁺ (mercurous ion). These cations are precipitated from any other cations that might be present in a sample by the addition of 6 M hydrochloric acid. Addition of HCl forms a mixture of AgCl, PbCl₂, and Hg₂Cl₂ solids. - Ag⁺(aq) + Cl⁻(aq) → AgCl(s) - Pb²⁺(aq) + 2Cl⁻(aq) → PbCl₂(s) - Hg₂²⁺(aq) + 2Cl⁻(aq) → Hg₂Cl₂(s) At this point, the sample is centrifuged and the precipitate of the Group I chlorides isolated (in a real analysis, the centrifugate from above the precipitate is saved for further analysis of the other group cations). Lead ion is then separated from silver and mercury by taking advantage of the fact that PbCl₂ is much more soluble in hot water than in cold water (the solubilities of AgCl and Hg₂Cl₂ do not vary much with temperature). Distilled water is added to the Group I mixed precipitate and the mixture is heated to dissolve PbCl₂. The mixture is then centrifuged quickly while still hot, and the centrifugate containing lead ion is removed from the remaining silver/mercury precipitate. The presence of lead ion is then confirmed by the addition of chromate ion, CrO₄²⁻, which forms a characteristic yellow precipitate with lead ion, PbCrO₄. The precipitate containing silver and mercurous ions is then treated with aqueous ammonia. Silver ion is complexed by ammonia; the precipitate of AgCl will dissolve and is removed after centrifugation. A black/gray residue in the centrifuge tube confirms the presence of mercury. The centrifugate containing complexed silver ion is then treated with acid, which reacts with ammonia allowing the reprecipitation of silver chloride. Alternatively, potassium iodide can be added,
Transcribed Image Text:# 15. Qualitative Analysis of the Group I Cations ## Objective A sample containing only the Group I cations will be analyzed for the presence of silver(I), mercury(I), and lead(II) ions. ## Introduction The Group I cations are those species that form chloride precipitates that are insoluble in acid. The group includes Ag⁺, Pb²⁺, and Hg₂²⁺ (mercurous ion). These cations are precipitated from any other cations that might be present in a sample by the addition of 6 M hydrochloric acid. Addition of HCl forms a mixture of AgCl, PbCl₂, and Hg₂Cl₂ solids. - Ag⁺(aq) + Cl⁻(aq) → AgCl(s) - Pb²⁺(aq) + 2Cl⁻(aq) → PbCl₂(s) - Hg₂²⁺(aq) + 2Cl⁻(aq) → Hg₂Cl₂(s) At this point, the sample is centrifuged and the precipitate of the Group I chlorides isolated (in a real analysis, the centrifugate from above the precipitate is saved for further analysis of the other group cations). Lead ion is then separated from silver and mercury by taking advantage of the fact that PbCl₂ is much more soluble in hot water than in cold water (the solubilities of AgCl and Hg₂Cl₂ do not vary much with temperature). Distilled water is added to the Group I mixed precipitate and the mixture is heated to dissolve PbCl₂. The mixture is then centrifuged quickly while still hot, and the centrifugate containing lead ion is removed from the remaining silver/mercury precipitate. The presence of lead ion is then confirmed by the addition of chromate ion, CrO₄²⁻, which forms a characteristic yellow precipitate with lead ion, PbCrO₄. The precipitate containing silver and mercurous ions is then treated with aqueous ammonia. Silver ion is complexed by ammonia; the precipitate of AgCl will dissolve and is removed after centrifugation. A black/gray residue in the centrifuge tube confirms the presence of mercury. The centrifugate containing complexed silver ion is then treated with acid, which reacts with ammonia allowing the reprecipitation of silver chloride. Alternatively, potassium iodide can be added,
**Qualitative Analysis of the Group I Cations** - **Date:** __________ - **Course:** __________ - **Section:** __________ - **Instructor:** __________ - **Student name:** __________ - **Team members:** __________ **Prelaboratory Questions** 1. The separation of lead chloride from the chlorides of silver and mercury(I) is based on the differing solubilities of these substances in cold and hot water. Use a handbook of chemical data to find the specific solubilities (in g/100 g H₂O) in both cold and hot water for AgCl, PbCl₂, and Hg₂Cl₂. | | Cold water | Hot water | Reference | |---------------|------------|-----------|-----------| | Silver chloride | ___________ | __________ | __________ | | Lead(II) chloride | ___________ | __________ | __________ | | Mercury(I) chloride | ___________ | __________ | __________ | 2. Because a qualitative analysis may often consist of a rather long series of manipulations, precipitations, centrifugations, and separations, flow charts are often prepared to summarize graphically the steps to be undertaken. For this analysis of Group I, prepare a simple flow chart showing what ions are present at each point in the procedure, what reagents are to be added, and the result to be expected at each point.
Transcribed Image Text:**Qualitative Analysis of the Group I Cations** - **Date:** __________ - **Course:** __________ - **Section:** __________ - **Instructor:** __________ - **Student name:** __________ - **Team members:** __________ **Prelaboratory Questions** 1. The separation of lead chloride from the chlorides of silver and mercury(I) is based on the differing solubilities of these substances in cold and hot water. Use a handbook of chemical data to find the specific solubilities (in g/100 g H₂O) in both cold and hot water for AgCl, PbCl₂, and Hg₂Cl₂. | | Cold water | Hot water | Reference | |---------------|------------|-----------|-----------| | Silver chloride | ___________ | __________ | __________ | | Lead(II) chloride | ___________ | __________ | __________ | | Mercury(I) chloride | ___________ | __________ | __________ | 2. Because a qualitative analysis may often consist of a rather long series of manipulations, precipitations, centrifugations, and separations, flow charts are often prepared to summarize graphically the steps to be undertaken. For this analysis of Group I, prepare a simple flow chart showing what ions are present at each point in the procedure, what reagents are to be added, and the result to be expected at each point.
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