Each copper(II) sulfate unit is associated with five water molecules in crystalline copper(II) sulfate pentahydrate $\left(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\right)$. When this compound is heated in air above $100^{\circ} \mathrm{C}$, it loses the water molecules and also its blue color: $$4 \mathrm{Au}+8 \mathrm{KCN}+\mathrm{O}_{2}+2 \mathrm{H}_{2} \mathrm{O} \underset{4 \mathrm{KAu}(\mathrm{CN})_{2}+4 \mathrm{KOH}}{\longrightarrow}$$ What is the minimum amount of KCN in moles needed to extract $29.0 \mathrm{~g}$ (about an ounce) of gold?

Name: Problem 74, Chapter 3: Chemistry
Uploaded: 2020-07-08T21:25:05-08:00
Duration: 1 min 26 s
Channel: Daniel Kim
Description: Each copper(II) sulfate unit is associated with five water molecules in crystalline copper(II) sulfate pentahydrate (CuSO4 ·5 H2 O). When this compound is heated in air above 100^∘ C, it loses the water molecules and also its blue color: 4 Au+8 KCN+O2+2 H2 O 4 KAu(CN)2+4 KOH⟶ What is the minimum amount of KCN in moles needed to extract 29.0 g (about an ounce) of gold?

   Each copper(II) sulfate unit is associated with five water molecules in crystalline copper(II) sulfate pentahydrate $\left(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\right)$. When this compound is heated in air above $100^{\circ} \mathrm{C}$, it loses the water molecules and also its blue color: $$4 \mathrm{Au}+8 \mathrm{KCN}+\mathrm{O}_{2}+2 \mathrm{H}_{2} \mathrm{O} \underset{4 \mathrm{KAu}(\mathrm{CN})_{2}+4 \mathrm{KOH}}{\longrightarrow}$$
What is the minimum amount of KCN in moles needed to extract $29.0 \mathrm{~g}$ (about an ounce) of gold?

Chemistry

Raymond Chang, Jason… 13th Edition

Chapter 3, Problem 74

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Solved by Expert Daniel Kim

07/08/2020

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The molar mass of gold is $197.0 \mathrm{~g/mol}$. Show more…

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Each copper(II) sulfate unit is associated with five water molecules in crystalline copper(II) sulfate pentahydrate $\left(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\right)$. When this compound is heated in air above $100^{\circ} \mathrm{C}$, it loses the water molecules and also its blue color: $$4 \mathrm{Au}+8 \mathrm{KCN}+\mathrm{O}_{2}+2 \mathrm{H}_{2} \mathrm{O} \underset{4 \mathrm{KAu}(\mathrm{CN})_{2}+4 \mathrm{KOH}}{\longrightarrow}$$ What is the minimum amount of KCN in moles needed to extract $29.0 \mathrm{~g}$ (about an ounce) of gold?