[20.100] Gold exists in two common positive oxidation states, +1 and +3. The standard reduction potentials for these oxida- tion states are Au*(aq) + e¯ - Au(s) Ered = +1.69 V Au** (aq) + 3 e – Au(s) Eed = +1.50 V (a) Can you use these data to explain why gold does not tar- nish in the air? (b) Suggest several substances that should be strong enough oxidizing agents to oxidize gold metal. (c) Miners obtain gold by soaking gold-containing ores in an aqueous solution of sodium cyanide. A very soluble com- plex ion of gold forms in the aqueous solution because of the redox reaction 4 Au(s) + 8 NaCN(aq) + 2 H,O(1) + O;(g) 4 Na[Au(CN);](aq) + 4 NaOH(aq) What is being oxidized and what is being reduced in this reac- tion? (d) 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. What is being oxi- dized, and what is being reduced?

[20.100] Gold exists in two common positive oxidation states, +1 and +3. The standard reduction potentials for these oxida- tion states are Au*(aq) + e¯ - Au(s) Ered = +1.69 V Au** (aq) + 3 e – Au(s) Eed = +1.50 V (a) Can you use these data to explain why gold does not tar- nish in the air? (b) Suggest several substances that should be strong enough oxidizing agents to oxidize gold metal. (c) Miners obtain gold by soaking gold-containing ores in an aqueous solution of sodium cyanide. A very soluble com- plex ion of gold forms in the aqueous solution because of the redox reaction 4 Au(s) + 8 NaCN(aq) + 2 H,O(1) + O;(g) 4 Na[Au(CN);](aq) + 4 NaOH(aq) What is being oxidized and what is being reduced in this reac- tion? (d) 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. What is being oxi- dized, and what is being reduced?

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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Concept explainers

Electrolysis

Electrolysis is defined as the process of breaking down ionic compounds into their constituent elements by passing a direct electric current through the compound in a fluid state. The cathode reduces cations, while the anode oxidizes anions. An electrolyte, electrodes, and some form of external power source are the main components required for conducting electrolysis. A partition, such as an ion-exchange membrane or a salt bridge, may also be used, but this is optional. These are primarily used to prevent the products from diffusing near the opposing electrode.

Question

[20.100] Gold exists in two common positive oxidation states, +1
and +3. The standard reduction potentials for these oxida-
tion states are
Au*(aq) + e
Au(s) Eed = +1.69 V
>
Au*(ag) + 3 e →
Au(s) Ered
= +1.50 V
(a) Can you use these data to explain why gold does not tar-
nish in the air? (b) Suggest several substances that should
be strong enough oxidizing agents to oxidize gold metal.
(c) Miners obtain gold by soaking gold-containing ores in
an aqueous solution of sodium cyanide. A very soluble com-
plex ion of gold forms in the aqueous solution because of the
redox reaction
4 Au(s) + 8 NaCN(aq) + 2 H,O(1) + O2(g)
4 Na[Au(CN),](aq) + 4 NaOH(aq)
>
What is being oxidized and what is being reduced in this reac-
tion? (d) 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. What is being oxi-
dized, and what is being reduced?

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