Question

The decomposition products of [FeO$_4$]$^{2-}$ are:

• A. Fe$_3$O$_4$, O$_2$
• B. FeO, O$_2$
• C. Fe$_2$O$_3$, O$_2$
• D. FeO, Fe$_2$O$_3$

Hint:

Ferrate ion [FeO$_4$]$^{2-}$ decomposes in aqueous medium forming Fe$_2$O$_3$ and oxygen due to its high oxidation state (+6).

Answer 1

The Correct Option is C

The ferrate ion, [FeO$_4$]$^{2-}$, is a powerful oxidizing agent. Upon decomposition, it forms ferric oxide (Fe$_2$O$_3$) and releases oxygen gas (O$_2$). The decomposition can be represented as: \[ 4\mathrm{FeO}_4^{2-} + 10\mathrm{H}_2\mathrm{O} \rightarrow 2\mathrm{Fe}_2\mathrm{O}_3 + 7\mathrm{O}_2 + 8\mathrm{OH}^- \] This reaction clearly shows that Fe$_2$O$_3$ and O$_2$ are the products of decomposition.

Answer 2

The decomposition products of [FeO₄]²⁻ are:

Step 1: Understand the nature of [FeO₄]²⁻ ion:
The ion [FeO₄]²⁻ is known as the ferrate(VI) ion. In this ion, iron is in the +6 oxidation state, which is highly unstable and strongly oxidizing in nature. Because of this instability, ferrate(VI) decomposes easily, especially in neutral or acidic solutions.

Step 2: Decomposition reaction:
Upon decomposition, ferrate(VI) gets reduced to iron(III) oxide (Fe₂O₃), which is a common and stable form of iron. Meanwhile, the oxygen atoms are released as molecular oxygen (O₂). This makes the decomposition a redox reaction, where Fe(VI) is reduced and oxygen is liberated.

Balanced decomposition reaction (in acidic/neutral medium):
\[ 4[FeO₄]^{2−} + 10H₂O \rightarrow 2Fe₂O₃ + 7O₂ + 8OH^− \]
(This simplified representation emphasizes that Fe₂O₃ and O₂ are the main decomposition products.)

Step 3: Products formed:
- Fe₂O₃: Iron(III) oxide (reddish-brown solid)
- O₂: Oxygen gas

Final Answer:
\[ \boxed{\text{Fe}_2\text{O}_3, \ \text{O}_2} \]