You can convert ferric chloride (FeCl3) to ferrous chloride (FeCl2) through a reduction reaction, where ferric iron (Fe3+) gains an electron to become ferrous iron (Fe2+). Several methods can achieve this.
Methods for Converting Ferric Chloride to Ferrous Chloride
Here are a couple of common methods:
1. Reduction with Stannous Chloride (SnCl2)
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The Reaction: Ferric chloride reacts with stannous chloride to produce ferrous chloride and stannic chloride.
2 FeCl3 + SnCl2 → 2 FeCl2 + SnCl4 -
Explanation: Stannous chloride (SnCl2) acts as a reducing agent, donating electrons to ferric chloride (FeCl3) to form ferrous chloride (FeCl2). Stannous chloride itself is oxidized to stannic chloride (SnCl4).
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Drawback: The resulting solution will contain both ferrous chloride (FeCl2) and stannic chloride (SnCl4), which may complicate downstream processes if pure ferrous chloride is required. Separating these two would be an additional step.
2. Reduction with Mercury (Hg)
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The Reaction: Ferric chloride reacts with mercury to produce ferrous chloride and mercurous chloride.
2 Hg + 2 FeCl3 → 2 FeCl2 + Hg2Cl2 -
Explanation: Elemental mercury (Hg) acts as a reducing agent, reducing ferric chloride (FeCl3) to ferrous chloride (FeCl2). Mercury is oxidized to mercurous chloride (Hg2Cl2), which is a solid that precipitates out of the solution.
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Considerations: Mercury is a toxic substance, so appropriate safety precautions must be taken when using this method. The precipitate, mercurous chloride, will need to be removed, typically by filtration.
Summary
Both stannous chloride and mercury can be used to reduce ferric chloride to ferrous chloride. The choice of method depends on factors like the required purity of the ferrous chloride product, safety considerations, and ease of separation of the resulting byproducts.
