Ch.4 - Chemical Quantities & Aqueous ReactionsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Solution: Qualitative analysis. A flowchart showing a common scheme for identifying cations.If a solution contained a mixture of Ag+ and Al3+ ions, would this separation scheme work?

Solution: Qualitative analysis. A flowchart showing a common scheme for identifying cations.If a solution contained a mixture of Ag+ and Al3+ ions, would this separation scheme work?

Problem

Qualitative analysis. A flowchart showing a common scheme for identifying cations.

A flowchart shows how to identify cations through qualitative analysis. The flowchart is presented here as an ordered list. Begin with a solution containing unknown metal cations: Add 6 molar HCl. Precipitate: Group 1 (insoluble chlorides: AgCl, PbCl2, Hg2Cl2). Precipitate: Group 1 (insoluble chlorides: AgCl, PbCl2, Hg2Cl2). Add H2S and 0.2 molar HCl. Precipitate: Group 2 (acid-insoluble sulfides: CuS, CdS, Bi2S3, PbS, HgS, As2S3, Sb2S3, SnS2). Decantate: remaining cations. Add (NH4) 2S at pH equals 8. Precipitate: Group 3 (base-insoluble sulfides and hydroxides: Al(OH) 3, Fe(OH)3, Cr(OH)3, ZnS, NiS, MnS, CoS). Decantate: remaining cations. Add (NH4)2HPO4 and NH3. Precipitate: Group 4 (Insoluble phosphates: Ca3 (PO4)2, Sr2 (PO4)2, Ba3(PO4)2, MgNH4PO4. Decantate: Group 5 (Alkali metal ions and NH4+).

If a solution contained a mixture of Ag+ and Al3+ ions, would this separation scheme work?

Solution

We are asked if this separation scheme would work if solution contained mixture of Ag+ and Al3+ ions.


Cations are positively charged ions. The cations in the solution can be separated by precipitating one out. 

We will refer to the solubility rules in order to determine if the scheme work to separate Ag+ and Al3+ ions in a mixture.


Solubility Rules:

Soluble Ionic Compounds:

 Group 1A ions (Li+, Na+, K+, etc.) and Ammonium ion (NH4+) are soluble
Nitrates (NO3-), Acetates (CH3COO- or C2H3O2-), and most Perchlorates (ClO4-) are soluble
Cl-, Br-, and I- are soluble except when paired with Ag+, Pb2+, Cu+, Hg22+
Sulfates (SO42-) are soluble except those of Ca2+, Sr2+, Ba2+, Ag+, and Pb2+

• Insoluble Ionic Compounds:

View the complete written solution...