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Ferric vs. Ferrous — What's the Difference?

By Tayyaba Rehman & Fiza Rafique — Updated on March 14, 2024
Ferric refers to iron with a +3 oxidation state, often forming reddish compounds, whereas ferrous indicates iron in a +2 oxidation state, typically forming greenish or bluish compounds.
Ferric vs. Ferrous — What's the Difference?

Difference Between Ferric and Ferrous


Key Differences

Ferric and ferrous compounds are two forms of iron differentiated primarily by their oxidation states: ferric (Fe^3+) and ferrous (Fe^2+). Ferric compounds, with iron in a +3 oxidation state, tend to form reddish-brown solutions or compounds, indicating their higher oxidation level. On the other hand, ferrous compounds, where iron is in a +2 oxidation state, usually appear greenish or bluish, reflecting their different electronic configuration.
In terms of chemical reactivity, ferric ions are less reactive compared to ferrous ions due to their higher oxidation state. Ferric ions have a stronger tendency to gain an electron to return to a more stable state, whereas ferrous ions, being in a lower oxidation state, are more reactive and more readily participate in oxidation-reduction reactions.
The solubility of ferric and ferrous compounds also differs in various environments. Ferrous compounds are generally more soluble in water than ferric compounds. This difference in solubility can significantly affect the bioavailability of iron in environmental and biological systems, impacting how organisms access and use iron.
In industrial applications, the distinction between ferric and ferrous compounds is crucial. Ferrous compounds are often used in the manufacturing of steel and other alloys due to their reactivity and strength. Ferric compounds, meanwhile, find their uses in water purification and as pigments due to their coagulating properties and color.
Environmental and health impacts of ferric and ferrous ions can vary. Ferrous ions are more readily absorbed by the human body, making them crucial for transporting oxygen in the body. Ferric ions, though also important, are less efficiently absorbed without being first reduced to the ferrous form within the digestive tract.

Comparison Chart

Oxidation State


Color of Compounds


Chemical Reactivity

Less reactive than ferrous
More reactive

Solubility in Water

Generally less soluble
Generally more soluble

Industrial Use

Water purification, pigments
Steel manufacturing, alloys

Compare with Definitions


Less reactive compared to ferrous compounds.
Ferric ions are more stable in oxidation-reduction reactions.


Indicates iron in the +2 oxidation state.
Ferrous sulfate is a common dietary supplement.


Refers to iron in the +3 oxidation state.
Ferric chloride is used in water treatment processes.


Key in steel manufacturing and alloys.
Ferrous metals are essential for construction and automotive industries.


Ferric compounds are less soluble in water.
Ferric hydroxide precipitates in neutral to basic solutions.


Compounds often appear greenish or bluish.
Ferrous sulfide gives off a greenish-black color.


Compounds usually appear reddish-brown.
Ferric oxide forms rust on iron surfaces.


Ferrous compounds are more soluble in water.
Ferrous chloride is used in water treatment for its solubility.


Used in water purification and as pigments.
Ferric salts are effective in coagulating contaminants.


More reactive and readily participates in redox reactions.
Ferrous iron is easily oxidized to ferric iron in the presence of oxygen.


Relating to iron.


In chemistry, the adjective ferrous indicates a compound that contains iron(II), meaning iron in its +2 oxidation state, possibly as the divalent cation Fe2+. It is opposed to "ferric" or iron(III), meaning iron in its +3 oxidation state, such as the trivalent cation Fe3+.


Relating to or containing iron, especially with valence 3 or a valence higher than in a corresponding ferrous compound.


(chiefly of metals) containing or consisting of iron.


Pertaining to, derived from, or containing iron.


Of iron with a valency of two; of iron(II).


(chemistry) Of compounds of iron in which it has a valence or oxidation number of 3


Relating to or containing iron, especially with valence 2 or a valence lower than in a corresponding ferric compound.


Pertaining to, derived from, or containing iron. Specifically (Chem.), denoting those compounds in which iron has a higher valence than in the ferrous compounds; as, ferric oxide; ferric acid.


Of or containing iron.


Of or relating to or containing iron


(chemistry) Of compounds of iron in which it has a valence or oxidation number of 2.


Pertaining to, or derived from, iron; - especially used of compounds of iron in which the iron has its lower valence of two; as, ferrous sulphate.


Of or relating to or containing iron

Common Curiosities

Can ferric ions become ferrous?

Yes, ferric ions can be reduced to ferrous ions in redox reactions.

How are ferrous compounds different from ferric?

Ferrous compounds have iron in a +2 oxidation state, making them more reactive than ferric compounds.

How does the solubility of ferric and ferrous compounds affect their applications?

Ferrous compounds' higher solubility makes them suitable for dietary supplements and steel manufacturing, while ferric compounds' lower solubility suits them for water treatment and pigments.

What defines ferric compounds?

Ferric compounds contain iron in a +3 oxidation state.

Why is ferrous iron more reactive than ferric iron?

Ferrous iron's lower oxidation state makes it more eager to participate in chemical reactions, including oxidation.

Are ferric and ferrous compounds safe?

Generally, they are safe in controlled applications, but excessive exposure can have environmental or health risks.

Why are ferrous compounds green or blue?

The green or blue color is due to the electronic configuration of the ferrous ion.

What are common uses of ferric compounds?

Ferric compounds are used in water purification and as pigments.

Can the body use ferric iron efficiently?

The body prefers ferrous iron for absorption; ferric iron must be reduced to ferrous iron in the digestive tract for efficient absorption.

What role does the oxidation state play in ferric and ferrous compounds?

The oxidation state affects their chemical reactivity, color, and applications.

How are ferric and ferrous compounds prepared industrially?

They are prepared through various chemical processes, including oxidation and reduction reactions.

How does the presence of ferric and ferrous ions affect water quality?

Their presence can indicate contamination levels and affect water treatment processes, influencing overall water quality.

Do ferric and ferrous ions occur naturally in the environment?

Yes, they naturally occur in various environmental settings, affecting soil chemistry and aquatic systems.

What happens to ferric and ferrous ions in water?

Ferrous ions can oxidize to ferric ions in water, especially if oxygen is present.

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Author Spotlight

Written by
Tayyaba Rehman
Tayyaba Rehman is a distinguished writer, currently serving as a primary contributor to As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
Co-written by
Fiza Rafique
Fiza Rafique is a skilled content writer at, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.

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