Copper was one of the earliest metals used by humans, because it can be prepared from a wide variety of copper minerals, such as cuprite (Cu2O), chalcocite (Cu2S), and malachite [Cu2CO3(OH)2]. Balance the following reactions for converting these minerals into copper metal. Place a coefficient in each gray box. (a) Cu2O(s) + C(s) rightarrow Cu(s) + CO2(g)
(b) Cu2O(s) + Cu2 S(s) rightarrow Cu(s) + SO2(g)
(c) Cu2 CO3 (OH)2(s) rightarrow CuO(s) + CO2(g) + H2O(g)
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a. 2 Cu₂O(s) + C(s) → 4Cu(s) + CO₂(g)

b. 2Cu₂O(s) + Cu₂S(s) → 6Cu(s) + SO₂(g)

c. Cu₂CO₃(OH)₂(s) → 2 CuO(s) + CO₂(g) + H₂O(g)

Explanation:

A reaction is balanced when you have the same amount of atoms in reactants and products.

In the reactions:

(a) Cu₂O(s) + C(s) → Cu(s) + CO₂(g)

As a general rule, you first balance oxygen and hydrogen. In products you have 2 oxygens, then:

2 Cu₂O(s) + C(s) → Cu(s) + CO₂(g)

Carbon is balanced yet. Thus, you need just to balance Cu:

2 Cu₂O(s) + C(s) → 4Cu(s) + CO₂(g)

(b) Cu₂O(s) + Cu₂S(s) → Cu(s) + SO₂(g)

Balancing oxygen:

2Cu₂O(s) + Cu₂S(s) → Cu(s) + SO₂(g)

Sulfur is balanced yet. Now you just need to balance Cu:

2Cu₂O(s) + Cu₂S(s) → 6Cu(s) + SO₂(g)

(c) Cu₂CO₃(OH)₂(s) → CuO(s) + CO₂(g) + H₂O(g)

This reaction is different because the reactant is a chemical with a lot of atoms. we will first balance Cu:

Cu₂CO₃(OH)₂(s) → 2 CuO(s) + CO₂(g) + H₂O(g)

Balancing copper, oxygen, hydrogen and carbon are balanced:

Cu₂CO₃(OH)₂(s) → 2 CuO(s) + CO₂(g) + H₂O(g)