Ch.18 - ElectrochemistryWorksheetSee 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: Gold exists in two common positive oxidation states, +1 and +3. The standard reduction potentials for these oxidation states areAu+ ( aq ) + e-  →  Au ( s )          Eredo= + 1.69 VAu3 +  ( aq ) + 3e-

Problem
Gold exists in two common positive oxidation states, +1 and +3. The standard reduction potentials for these oxidation states are
Au+ ( aq ) + e-  →  Au ( s )          Eredo= + 1.69 V
Au3 +  ( aq ) + 3e-  →  Au( s )      Eredo= + 1.50 V


Miners obtain gold by soaking gold-containing ores in an aqueous solution of sodium cyanide. A very soluble complex ion of gold forms in the aqueous solution because of the redox reaction
4 Au ( s ) + 8 NaCN ( aq ) + 2 H2O( l ) + O2 ( g )  →   4 Na[Au(CN)2]( aq ) + 4 NaOH ( aq )

Gold miners then react the basic aqueous product solution from part C with Zn dust to get gold metal. Write a balanced redox reaction for this process.