What are the oxidizing and reducing agents in this reaction?
\( \mathrm{ClO^-(aq)+SO_2(g)+H_2O(l)\rightarrow Cl^-(aq)+SO_4^{2-}(aq)+2H^+(aq)} \)
| Oxidizing agent | Reducing agent | |
|---|---|---|
| A. | \( \mathrm{ClO^-} \) | \( \mathrm{H_2O} \) |
| B. | \( \mathrm{SO_2} \) | \( \mathrm{SO_4^{2-}} \) |
| C. | \( \mathrm{SO_2} \) | \( \mathrm{ClO^-} \) |
| D. | \( \mathrm{ClO^-} \) | \( \mathrm{SO_2} \) |
Correct Answer: \( \boxed{\mathrm{D}} \)
In \( \mathrm{ClO^-} \), chlorine has oxidation state \(+1\). In \( \mathrm{Cl^-} \), chlorine has oxidation state \(-1\). Chlorine is therefore reduced:
\( \mathrm{Cl^{+1}\rightarrow Cl^{-1}} \)
The species that is reduced acts as the oxidizing agent. Therefore, \( \mathrm{ClO^-} \) is the oxidizing agent.
In \( \mathrm{SO_2} \), sulfur has oxidation state \(+4\). In \( \mathrm{SO_4^{2-}} \), sulfur has oxidation state \(+6\). Sulfur is therefore oxidized:
\( \mathrm{S^{+4}\rightarrow S^{+6}} \)
The species that is oxidized acts as the reducing agent. Therefore, \( \mathrm{SO_2} \) is the reducing agent.
Therefore, the correct answer is (D).
Which statement about electrochemical cells is correct?
Correct Answer: \( \boxed{\mathrm{C}} \)
A secondary cell, such as a rechargeable battery, can be recharged by supplying electrical energy. The electrical energy drives the redox reaction in the reverse direction, regenerating the original reactants.
Primary (voltaic) cells are designed for one-way spontaneous redox reactions and are generally not rechargeable.
Electrolytic cells use electrical energy to drive a non-spontaneous redox reaction, but being an electrolytic cell does not itself mean that the cell is rechargeable.
Therefore, the correct answer is (C).
| Option | Energy change | Spontaneity |
|---|---|---|
| A | chemical to electrical | non-spontaneous |
| B | electrical to chemical | non-spontaneous |
| C | chemical to electrical | spontaneous |
| D | electrical to chemical | spontaneous |
An electrolytic cell:
This means the energy conversion is:
electrical → chemical
and the process is:
non-spontaneous
Only option B matches both requirements.
✅ Answer: (B)
