Question

Difficulty: MediumCopper: Extraction, Physical and Chemical Properties, and Compounds
In the auto-reduction stage of copper extraction, copper(I) oxide (Cu2O\text{Cu}_2\text{O}) reacts with copper(I) sulfide (Cu2S\text{Cu}_2\text{S}) according to the following balanced equation:
Cu2S (s)+2Cu2O (s)6Cu (s)+SO2 (g)\text{Cu}_2\text{S (s)} + 2\text{Cu}_2\text{O (s)} \rightarrow 6\text{Cu (s)} + \text{SO}_2\text{ (g)}
If 14.3 g14.3\text{ g} of copper(I) oxide reacts completely with excess copper(I) sulfide, what mass of metallic copper in grams is produced? [Cu=63.5,O=16.0][\text{Cu} = 63.5, \text{O} = 16.0]

Answer: 19.05 g

Answer

The mass of metallic copper produced is 19.05 g.
According to the balanced chemical equation, 2 moles of copper(I) oxide react with copper(I) sulfide to yield 6 moles of metallic copper, which simplifies to a 1:3 molar ratio. Given that the molar mass of Cu2O is 143 g/mol, 14.3 g represents 0.1 mol of Cu2O. Based on the 1:3 ratio, this produces 0.3 mol of copper metal, corresponding to 19.05 g of Cu.

Step-by-Step Solution

1
Calculate the molar mass of copper(I) oxide
Molar mass of Cu2O = 143.0 g/mol
Required to convert the given mass of reactant to moles.
2
Determine moles of Cu2O reacted
Moles of Cu2O = 14.3 g / 143.0 g/mol = 0.10 mol
Establishes the quantitative amount of Cu2O in the chemical system.
3
Determine moles of copper metal produced using stoichiometry
Moles of Cu = 0.10 mol * (6 / 2) = 0.30 mol
The balanced chemical equation shows 2 moles of Cu2O yield 6 moles of Cu metal.
4
Calculate the mass of copper metal produced
Mass of Cu = 0.30 mol * 63.5 g/mol = 19.05 g
Converts the stoichiometric amount of product moles into grams.

Key Concept

Auto-reduction in copper extraction and stoichiometric mass calculations
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