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. After which step would the first precipitate be observed?

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+).

After which step would the first precipitate be observed?