Question

Mohr's salt has the formula

• A. \( \text{FeSO}_4 \cdot 7\text{H}_2\text{O} \)
• B. \( \text{FeSO}_4(\text{NH}_4)_2\text{SO}_4 \cdot 6\text{H}_2\text{O} \)
• C. \( \text{Fe}(\text{SO}_4)_3(\text{NH}_4)_2\text{SO}_4 \cdot 6\text{H}_2\text{O} \)
• D. \( \text{MgSO}_4 \cdot 7\text{H}_2\text{O} \)

Hint:

When studying salts like Mohr's salt, remember that double salts like FeSO\(_4\)(NH\(_4\))\(_2\)SO\(_4\) crystallize with a specific number of water molecules. Mohr's salt contains 6 water molecules of crystallization.

Answer 1

The Correct Option is B

Mohr's salt is a double salt which contains two types of cations, specifically iron (Fe²⁺) and ammonium (NH₄⁺), and one type of anion, sulfate (SO₄^2-). Additionally, it includes water of crystallization.

Each unit of Mohr's salt is composed as follows:

• 1 molecule of ferrous sulfate (FeSO₄)
• 1 molecule of ammonium sulfate [(NH₄)₂SO₄]
• 6 molecules of water of crystallization (6H₂O)

Combining these components gives the chemical formula:

${\mathrm{Fe}\mathrm{SO}}_4{(\mathrm{NH})}_4{\mathrm{SO}}_4\cdot 6H_{2}O$

This is precisely the chemical formula of Mohr's salt. Therefore, the correct answer is:

\(\text{FeSO}_4(\text{NH}_4)_2\text{SO}_4 \cdot 6\text{H}_2\text{O}\)

Answer 2

Mohr's salt is a double salt which is a combination of ferrous sulfate \((\text{FeSO}_4)\), ammonium sulfate \((\text{(NH}_4)_2\text{SO}_4)\), and water of crystallization. It is known for having the ability to maintain a stable oxidation state of iron (+2). The chemical formula of Mohr's salt is:

\( \text{FeSO}_4(\text{NH}_4)_2\text{SO}_4 \cdot 6\text{H}_2\text{O} \)

This formula represents ferrous ammonium sulfate hexahydrate. Mohr's salt crystallizes with 6 molecules of water and is a green crystalline solid. It is named after the scientist who developed it, and is often used in titration experiments in analytical chemistry due to its stable, well-defined composition. Thus, the correct answer is:

\( \text{FeSO}_4(\text{NH}_4)_2\text{SO}_4 \cdot 6\text{H}_2\text{O} \)