Reaction of Hexaaquairon (ii)(iii) with Carbonate Ion (CO3) and Thiocyanate Ion (SCN) #pashtolecture

Reaction of Hexaaquairon (ii)(iii) with Carbonate Ion (CO3) and Thiocyanate Ion (SCN) #pashtolecture

#hexaaquairon(ii) #hexaaquairon(iii) #reactionwithCO3 #Carbonatesion #Thiocynateion #SCNion #xploretheworldofchemistry #chemistry #education #chemistryofclass10 #chemistryclass12 #chemistry9th #chemistryofclass11

Here are the important reactions of **hexaaquairon(II) and hexaaquairon(III) ions** with **carbonate (CO₃²⁻)** and **thiocyanate (SCN⁻)** in a clear, exam-focused way:

---

# 🔷 1. Reaction with Carbonate Ion (CO₃²⁻)

## 🟢 (a) Hexaaquairon(II) → [Fe(H₂O)₆]²⁺

* The Fe²⁺ ion is **weakly acidic**, so carbonate acts as a **base**.
* Instead of forming FeCO₃ directly, it gives a **precipitate of iron(II) hydroxide**.

### Reaction:

[
[Fe(H_2O)_6]^{2+} + CO_3^{2-} \rightarrow Fe(OH)_2(s) + CO_2(g) + H_2O(l)
]

### Observations:

* Pale green precipitate of **Fe(OH)₂**
* Effervescence of **CO₂ gas**

---

## 🟡 (b) Hexaaquairon(III) → [Fe(H₂O)₆]³⁺

* Fe³⁺ is **more acidic**, so it strongly reacts with carbonate.
* Produces **iron(III) hydroxide precipitate**.

### Reaction:

[
[Fe(H_2O)_6]^{3+} + CO_3^{2-} \rightarrow Fe(OH)_3(s) + CO_2(g) + H_2O(l)
]

### Observations:

* Reddish-brown precipitate of **Fe(OH)₃**
* Effervescence of CO₂

---

# 🔷 2. Reaction with Thiocyanate Ion (SCN⁻)

## 🟢 (a) Hexaaquairon(II) → [Fe(H₂O)₆]²⁺

* Fe²⁺ shows **very weak or no visible reaction** with SCN⁻.
* No significant color change.

👉 **Conclusion:**
No important complex formation (not used for testing Fe²⁺).

---

## 🔴 (b) Hexaaquairon(III) → [Fe(H₂O)₆]³⁺

* Fe³⁺ reacts strongly with SCN⁻ to form a **blood-red complex**.

### Reaction:

[
[Fe(H_2O)_6]^{3+} + SCN^- \rightarrow [FeSCN(H_2O)_5]^{2+}
]

### Observations:

* Deep **blood-red color**
* Formation of **thiocyanatoiron(III) complex**

👉 This is a **very important qualitative test for Fe³⁺**.

---

# ⭐ Summary Table

| Ion | With CO₃²⁻ | With SCN⁻ |
| -------- | ------------------------- | ----------------- |
| **Fe²⁺** | Fe(OH)₂ (green ppt) + CO₂ | No reaction |
| **Fe³⁺** | Fe(OH)₃ (brown ppt) + CO₂ | Blood-red complex |

---

If you want, I can also give **mechanism (stepwise ligand substitution & hydrolysis)** or **MCQs for exams** 👍