Ch.16 - Aqueous Equilibrium WorksheetSee 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: Selective precipitation. In this example Cu2+ ions are separated from Zn2+ ions.What would happen if the pH were raised to 8 first and then H2S were added?

Problem

A test tube containing a blue liquid has a pH of approximately 1 and has a solution containing Zn 2+ (aqueous) and Cu 2+ (aqueous), in addition to H+ ions. When H2S is added to a solution whose pH exceeds 0.6, CuS precipitates; the test tube is now clear with a solid precipitate on the bottom; pH remains around 1.  After CuS is removed, the pH is increased, allowing ZnS to precipitate; pH is approximately 8.
Selective precipitation. In this example Cu2+ ions are separated from Zn2+ ions.

What would happen if the pH were raised to 8 first and then H2S were added?