Question

3cu²⁺ + 2cr → 2cr³⁺ + 3cu
which of these represents the line notation of the spontaneous cell?
a. cu | cu²⁺(1.0 m) || cr³⁺(1.0 m) | cr
b. cu²⁺(1.0 m) | cu || cr | cr³⁺(1.0 m)
c. cr | cr³⁺(1.0 m) || cu²⁺(1.0 m) | cu
d. cr³⁺(1.0 m) | cr || cu | cu²⁺(1.0 m)
enter the answer choice letter.

Explanation:

To determine the line notation of a spontaneous electrochemical cell, we first identify the oxidation and reduction half - reactions. In the given reaction \(3\text{Cu}^{2+}+2\text{Cr}
ightarrow2\text{Cr}^{3+}+3\text{Cu}\), Chromium (Cr) is oxidized (loses electrons: \(\text{Cr}
ightarrow\text{Cr}^{3+}+ 3e^-\)) and Copper(II) ion (\(\text{Cu}^{2+}\)) is reduced (gains electrons: \(\text{Cu}^{2+}+2e^-
ightarrow\text{Cu}\)).

In line notation, the anode (where oxidation occurs) is on the left, and the cathode (where reduction occurs) is on the right. The anode is the species being oxidized (Cr in its elemental form and then \(Cr^{3+}\) in solution), and the cathode is the species being reduced (\(Cu^{2+}\) in solution and then Cu in its elemental form).

For option C: \(Cr|Cr^{3+}(1.0\ M)||Cu^{2+}(1.0\ M)|Cu\), the left side (\(Cr|Cr^{3+}\)) represents the anode (oxidation: \(Cr
ightarrow Cr^{3+}+3e^-\)) and the right side (\(Cu^{2+}|Cu\)) represents the cathode (reduction: \(Cu^{2+}+2e^-
ightarrow Cu\)), which is consistent with the redox reaction and the requirements for line notation of a spontaneous cell.

Option A has the anode and cathode reversed (Cu is being oxidized and Cr is being reduced, which is not the case in the given reaction). Option B also has the anode and cathode reversed in terms of the species order for oxidation and reduction. Option D has the oxidized and reduced species in the wrong order for both anode and cathode.

Answer:

C