Question

Which of the following ions is the strongest oxidizing agent? (Atomic Number of Ce = 58, Eu = 63, Tb = 65, Lu = 71)

• A. \( {Lu}^{3+} \)
• B. \( {Eu}^{2+} \)
• C. \( {Tb}^{4+} \)
• D. \( {Ce}^{3+} \)

Hint:

Ions with a higher charge and smaller size are generally stronger oxidizing agents because they have a higher tendency to accept electrons and achieve a stable electronic configuration.

Answer 1

The Correct Option is C

The question asks us to identify the strongest oxidizing agent among the given ions. To determine this, we need to understand the concept of oxidizing agents. 

An oxidizing agent is a substance that has the ability to oxidize other substances, i.e., it gains electrons and is reduced itself. The strength of an oxidizing agent is typically determined by its tendency to accept electrons.

Let's evaluate each option:

• \({Lu}^{3+}\): Lutetium has completed f-electron shells (4f¹⁴), which gives it stability and a low tendency to accept electrons.
• \({Eu}^{2+}\): Europium in its +2 state tends to revert to the more stable +3 state (Eu³⁺), making it a moderate oxidizing agent but not very strong.
• \({Tb}^{4+}\): Terbium in the +4 state tends to gain an electron to form the more stable +3 state (Tb³⁺), making it a strong oxidizing agent.
• \({Ce}^{3+}\): Cerium in the +3 state can further oxidize to the +4 state (Ce⁴⁺) under certain conditions, thus acting as a mild oxidizing agent.

The ion \({Tb}^{4+}\) is the strongest oxidizing agent among the given options. This is because it tends to effectively accept an electron owing to the stability associated with the conversion from +4 to +3 oxidation state.

In conclusion, the correct answer is \({Tb}^{4+}\).

Answer 2

Strength of an Oxidizing Agent 

Given: The strength of an oxidizing agent depends on its ability to accept electrons. A higher positive charge and smaller size typically make an ion a stronger oxidizing agent because the ion is more eager to accept electrons to achieve a stable electronic configuration.

Analysis of Each Ion

1. \( \text{Lu}^{3+} \)

- This is the 3+ cation of lanthanum (atomic number 71). - Although it is a highly charged ion, it is relatively large compared to other lanthanides. - **Conclusion**: It is a strong oxidizing agent but not as strong as other ions with higher charges and smaller sizes.

2. \( \text{Eu}^{2+} \)

- This is the 2+ cation of europium (atomic number 63). - The Eu\(^{2+}\) ion is in the +2 oxidation state and is a stronger reducing agent compared to its +3 oxidation state. - **Conclusion**: Eu\(^{2+}\) is a reducing agent and not an oxidizing agent.

3. \( \text{Tb}^{4+} \)

- This is the 4+ cation of terbium (atomic number 65). - The Tb\(^{4+}\) ion is highly charged and has a very high tendency to accept electrons, making it a very strong oxidizing agent. - **Conclusion**: The Tb\(^{4+}\) ion is the strongest oxidizing agent among the ions listed.

4. \( \text{Ce}^{3+} \)

- This is the 3+ cation of cerium (atomic number 58). - The Ce\(^{3+}\) ion is a strong oxidizing agent but not as strong as Tb\(^{4+}\). - **Conclusion**: While a strong oxidizing agent, it is weaker compared to Tb\(^{4+}\).

Conclusion:

The strongest oxidizing agent among the given ions is \( \boxed{\text{Tb}^{4+}} \), which is the most eager to accept electrons due to its high charge and smaller size compared to the other ions.