Problem: Gold is isolated from rocks by reaction with aqueous cyanide, CN-:4 Au(s) + 8 NaCN(aq) + O2(g) + H2O(l)  →  4 Na[Au(CN)2](aq) + 4 NaOH(aq)The [Au(CN)2]- ion can be converted back to Au(0) by reaction with Zn(s) powder. Write a balanced chemical equation for this reaction.

FREE Expert Solution

[Au(CN)2]-(aq) → Au+(aq) + 2 CN-(aq)

Au+ → Au (gain 1 electrons → reduction)

Zn → Zn2+ (lose 2 electrons → oxidation)

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Problem Details

Gold is isolated from rocks by reaction with aqueous cyanide, CN-:

4 Au(s) + 8 NaCN(aq) + O2(g) + H2O(l)  →  4 Na[Au(CN)2](aq) + 4 NaOH(aq)

The [Au(CN)2]- ion can be converted back to Au(0) by reaction with Zn(s) powder. Write a balanced chemical equation for this reaction.

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