Question

In the balanced redox reaction: 2 cu(s) + s(s) ® cu2s(s), how many electrons are gained or lost by each copper atom? select one:
a. each copper atom gains two (2) electrons.
b. each copper atom gains one (1) electron.
c. each copper atom loses one (1) electron.
d. each copper atom loses two (2) electrons.

Answer 1

The answer: C) each copper atom loses one (1) electron.

2Cu + S ⇒ Cu₂S

2Cu⁰ ⇒ 2Cu⁺ + 2e⁻    oxydation

2e⁻ + S⁰ ⇒ S⁻²            reduction 

In the reaction, copper is oxidized and it releases an electron and transfers it to the sulfur atom. In contrast to copper, sulfur is reduced and it receives two electrons.

Answer 2

Answer: Option (c) is the correct answer.

Explanation:

The given reaction equation is as follows.

            $2Cu(s) + S(s) \rightarrow Cu_{2}S(s)$

The oxidation-reduction half reactions will be as follows.

Oxidation : $Cu(s) \rightarrow Cu^{+} + 1e^{-}$

Reduction: $S(s) + 2e^{-} \rightarrow S^{2-}$

By balancing the above half reactions, oxidation-half reaction will be as follows.

              $2Cu(s) \rightarrow 2Cu^{+} + 2e^{-}$

Whereas reduction-half reaction will remain the same.

Hence, it shows that each copper atom is losing one electron to combine with a sulfur atom.

Therefore, we can conclude that each copper atom loses one (1) electron.