Iron Chloride(FeCl2) Properties(25 Facts You Should Know)

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Iron chloride is an inorganic solid, also known as Ferrous chloride in chemistry. Let us explore the array of properties of Iron chloride.

Iron chloride is a stable halide of Iron; thermodynamically more stable than FeCl3(Ferric chloride). Iron chloride absorbs moisture from the air (hygroscopic in nature) and form hydrates.

We will discuss here the melting point, boiling point, conductivity, and reactivity of Iron chloride with detailed explanations.

FeCl2 IUPAC name

The IUPAC name (International Union of Pure and Applied Chemistry) of FeCl2 is Iron (II) chloride.

FeCl2 chemical formula

The chemical formula of Ferrous chloride is FeCl2. In this formula, Iron is the central atom that is singly bonded with two chlorine atoms.

FeCl2 CAS number

The CAS registry number (Chemical Abstracts Service) of FeCl2 is 7758-94-3.

FeCl2 ChemSpider ID

The ChemSpider ID (chemical structure database) of FeCl2 is 22866.

FeCl2 chemical classification

  • FeCl2 can be classified as an inorganic compound.
  • FeCl2 is a dihalide of iron that is generally off-white in appearance and also forms dihydrate and tetrahydrate.
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Structure of Iron chloride

FeCl2 molar mass

The molar mass of Iron chloride in anhydrous form is 126.75 g/mol. The molar mass of tetrahydrate is 198.81 g/mol.

FeCl2 color

Iron chloride is a white crystalline solid. It is generally white hexagonal crystals that sometimes appear green.

FeCl2 molar density

The molar density of FeCl2 is 0.025 mol/cm3 as its density is reported as 3.16 g/cm3.

          Compound               Formula          Density
          anhydrous        FeCl23.16 g/cm3
          dihydrate     FeCl2.2H2O2.93 g/cm3
          tetrahydrate      FeCl2.4H2O1.39 g/cm3
Density of Iron chloride

FeCl2 melting point

The melting point of FeCl2 is 674 °C or 950 K or 1251 °F.

FeCl2 boiling point

The boiling point of FeCl2 is 1023 °C or 1269 K or 1873 °F.

FeCl2 state at room temperature

FeCl2 exists as a solid at room temperature.

FeCl2 ionic/covalent bond

Ferrous chloride is an ionic compound. The large electronegative difference between the cation and anion makes it an ionic halide of Iron. However, the compound has also shown some covalent character which can be explained as per Fajans` rules.

FeCl2 ionic radius

The ionic radius of Fe2+ is found to be 77 pm.

FeCl2 electron configurations

The arrangement of electrons in atomic or molecular orbitals around the nucleus of an atom is called electronic configuration. Let us study the electronic configuration of FeCl2.

  • In FeCl2, the iron is in +2 oxidation state and it will have six electrons in the d sub-shell. So, its valence electronic configuration will be [Ar]3d6.
  • Furthermore, since Fe is coordinated with two chlorine atoms, the electronic configuration of the chloride ion must be [Ne]3s23p6.

FeCl2 oxidation state

  • The oxidation state of the central atom, Iron in FeCl2 is +2.
  • Each of the two Chlorine atoms is in -1 oxidation state.

FeCl2 acidity

The aqueous solution of FeCl2 is acidic.  The solution of Iron chloride is slightly acidic in nature with a pKa of 1.8 x 10-7. This gives a pH of 3.9 for a 0.1 molar solution of FeCl2.

Is FeCl2 odourless

FeCl2 has no specific odour.

Is FeCl2 paramagnetic

The substances that are weakly attracted to the externally applied magnetic field are found to show paramagnetic behavior. Let us see if iron chloride is paramagnetic or not.

FeCl2 is paramagnetic in nature. The central atom, Fe has four unpaired electrons in d-orbitals, making this compound paramagnetic.

FeCl2 hydrates

FeCl2 forms dihydrates (FeCl2.2H2O)and tetrahydrates (FeCl2.4H2O) that are pale green and green in color, respectively.

FeCl2 crystal structure

FeCl2 possesses hexagonal crystal lattice and the tetrahydrate of FeCl2 has monoclinic crystal structure.

  • The hexagonal crystal structure of FeCl2 has the dimensions, a=b=3.51 Å, c=6.18 Å and γ= 120°.
  • The monoclinic crystal structure of tetrahydrate (FeCl2.4H2O) has the dimensions, a = 5.91 Å, b = 7.71 Å, c = 8.84 Å and β = 112°.

FeCl2 polarity and conductivity

FeCl2 is ionic in nature and produces ions in solution.

  • FeCl2 is polar in nature. Due to the high charge difference between iron and chlorine, it shows polarity.
  • FeCl2 gets fully ionized in water producing Fe2+ and Cl– ions. If electricity is passed through this solution, it conducts electricity. FeCl2 behaves as a strong electrolyte in solution.

FeCl2 reaction with acid

  • FeCl2 does not react with acid because FeCl2 is stable in acids.

FeCl2 reaction with base

FeCl2 solution reacts with the base to form ferrous hydroxide and salt. It reacts with potassium hydroxide to give Ferrous hydroxide and potassium chloride.

  FeCl2(aq)+ 2KOH(aq)   →     Fe(OH)2(s)+ 2KCl(aq)

  FeCl2(aq) + 2NaOH(aq) →   Fe(OH)2(s) + 2NaCl(aq)

FeCl2 reaction with oxide

  • FeCl2 reacts with oxygen to give FeCl3 (Ferric chloride). On reaction with oxide above 250°C (523K), FeCl2 undergoes oxidation to give FeOCl (Iron oxychloride) and FeCl3 gas. The reaction is as follows,

2FeCl2(s) + 1/2O2(g) → FeOCl(s) + FeCl3(g)

  • FeOCl further reacts with oxygen to give Fe2O3 and chlorine gas;

       2FeOCl(s) + 1/2O2(g) → Fe2O3(s) + Cl2(g)

  • Also, the gaseous FeCl3 formed in the first step will also react with oxygen to form Fe2O3 and chlorine gas above 370°C (643K);

       2FeCl3(g) + 3/2 O2(g) → Fe2O3(s) + 3Cl2(g)

FeCl2 reaction with metal

On reaction with highly reactive metals like sodium, FeCl2 undergoes displacement reaction.

  2Na(s) + FeCl2(aq) → 2NaCl(aq) + Fe(s)

Conclusion

FeCl2 is a hygroscopic white crystalline ionic compound that is highly soluble in water and has a very high melting point and good conductivity. Iron chloride is widely used in sewage water treatment. It also has applications in medicinal chemistry, textile industry and is often used as a precursor in organic synthesis.