Properties of Mohr’s Salt
Ferrous ammonium sulfate hexahydrate, also known as Mohr’s salt ((NH4)2Fe(SO4)2·6H2O), has several interesting physical and chemical characteristics. The properties of Mohr’s Salt can be understood easily under the following heads below:
Physical Properties
The physical properties of Mohr’s Salt can be understood by the table below:
|
Properties of Mohr’s Salt |
|
|---|---|
|
Chemical Formula |
(NH4)2Fe(SO4)2·6H2O |
|
Chemical Name |
Ferrous ammonium sulfate hexahydrate |
|
Physical State |
Crystalline solid |
|
Crystal Structure |
Monoclinic |
|
Color |
Light Green |
|
Solubility in Water |
Soluble (increases with temperature) |
|
Magnetic Properties |
Exhibits magnetic properties due to iron(II) ions |
|
Color Change upon Oxidation |
May change from green to brown upon exposure to air |
Chemical Properties of Mohr’s Salt
The chemical properties of Mohr’s Salt are as follows:
1. Reaction with Alkalis: Mohr’s salt reacts with alkalis to form insoluble hydroxides. For example:
(NH4)2Fe(SO4)2.6H2O + 2NaOH → Fe(OH)2 + 2(NH4)2SO4 + 6H2O
2. Formation of Ferric Salt: Mohr’s salt can be oxidized to form ferric sulfate in the presence of oxidizing agents.
(NH4)2Fe(SO4)2.6H2O + Br2 → Fe2(SO4)3 + 2NH4Br + 6H2O
3. Decomposition upon Heating: Mohr’s salt undergoes thermal decomposition upon heating, releasing ammonia, sulfur dioxide, and water vapor.
(NH4)2Fe(SO4)2.6H2O→FeSO4 + (NH4)4SO4 + 6H2O
4. Oxidation by Air: In the presence of air, the iron(II) ions in Mohr’s salt can oxidize to iron(III) ions (Fe³⁺). This oxidation is often observable as a color change from green to brown.
Mohr’s Salt
Mohr’s Salt is named after the German chemist Karl Friedrich Mohr, who synthesized it in 1855. In analytical chemistry, Mohr’s salt is frequently used as a primary standard to standardize solutions of other substances, especially when titrating permanganate solutions. In addition, it finds use as a fertilizer in agriculture and various laboratory applications. In this article, we will discuss the various concepts related to Mohr’s Salt.
Table of Content
- What is Mohr’s Salt?
- Structure of Mohr’s Salt – IIT JEE
- Formula for Mohr’s Salt
- Preparation of Mohr’s Salt
- Properties of Mohr’s Salt
- Double Salt
- Uses of Mohr’s Salt
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