15 Facts on HF + Fe2O3: What, How to Balance & FAQs

Hydrofluoric acid which is a weak acid reacts with ferric oxide which is a amphoteric oxide to undergo neutralization reaction. Let us now discuss the reaction: HF + Fe2O3.

Hydrogen fluoride (HF) is a colourless solution that acts as a weak acid. It does not dissociate in water completely. Ferric oxide, also called Hematite, is a reddish-brown odorless solution prepared by oxidation of iron. It is an amphoteric oxide naturally occurring in rocks having both acidic and basic properties.

In the following article we will discuss about the reaction, method of balancing, intermolecular forces, ionic equation, and various other facts about the reaction between HF and Fe2O3.

What is the product of HF and Fe2O3?

Ferric fluoride( FeF3) is obtained as the salt along with water after the reaction of hydrofluoric acid and ferric oxide.

HF + Fe2O3 = H2O + FeF3

What type of reaction is HF + Fe2O3?

The reaction HF + Fe2O3 is an acid-base neutralization reaction, where HF is weak acid and Fe2O3 is an amphoteric oxide.

How to balance HF + Fe2O3?

The reaction HF + Fe2O3 = H2O + FeF3 is not balanced.

 We have to balance the given equation in the following way:

  • The reactants and the products are labeled by a, b, c, d and e variables to represent the unknown coefficients.
  • aHF + b Fe2O3= cH2O + d FeF3
  • The same type of elements is rearranged together, and then the coefficients are equated.
  • After rearranging by their stoichiometric proportion, we get
  • Fe= 2a = d; O = 3a=c; H=b=2c; F=b=3d
  • Now we use the Gaussian elimination method to determine the values of the coefficients
  • We get a=1 , b=6  ,c=3  , d=2
  • Hence  the overall balanced equation is:
  • HF + 6Fe2O3 = 3H2O + 2FeF3

HF + Fe2O3 titration

The titration of Fe2O3 using HF is very difficult since HF is a strong acid and Fe2O3 is amphoteric in nature. Thus determination of end point in the titration process is very much difficult.


  • Conical flask
  • Beakers
  • Filter Paper
  • Bunsen Burner
  • Silica Crucible

Chemicals Required

Hydroflouric acid, Dilute nitric acid, ammonia


  • The oxide is dissolved in the hydroflouric acid medium in a conical flask.
  • The conical flask is heated and stirred with ammonia along with a few drops of dilute nitric acid.
  • The medium is washed to keep away impurities. The solution is filtered and washed again.
  • A sticky reddish precipitate is obtained which is soluble in dilute acids
  • The precipitate is heated and dried to measure purity. A few pieces of filter paper are added and the process is repeated.
  • The amount of Ferric oxide obtained is measured, and weight of Iron is found by mathematical calculation.
  • The weight of Fe2O3 = Weight of the crucible along with the residue – Weight of the empty crucible.

HF + Fe2O3 net ionic equation

The net ionic equation for the reaction HF + Fe2O3 is –

H+ + F + 6Fe2O3 = 2H2O+ 2FeF3

The ionic equation is derived by using the following steps:

  • Firstly the chemical states are indicated in the equation:
  • HF (aq.) + 6Fe2O3 (s) = 3H2O(l) + 2FeF3 (s)
  • Then the corresponding compounds are split into their ionic forms as follows:
  • H+(aq) + F(aq) +6Fe2O3 (s) = 2H2O(l) + 2FeF3(s)
  • The net ionic equation is:
  • H+ + F + 6Fe2O3 = 2H2O+ 2FeF3

HF + Fe2O3 conjugate pairs

The conjugate pairs of HF + Fe2O3 are:

  • The conjugate base for HF is F.
  • There exists no conjugate pair for Fe2O3 because it is amphoteric in nature.

HF and Fe2O3 intermolecular forces

HF and Fe2O3 has the following intermolecular forces:

  • There is a strong dipole-dipole interaction between the ions of HF molecule, since it is a polar molecule
  • Fe2O3 is a ionic compound thus the ions has electrostatic force of attraction between them.

HF + Fe2O3 reaction enthalpy

HF+ Fe2O3 reaction enthalpy is -18.33 KJ/mol, and is calculated as follows.

Table for Enthalpy value

The formula for enthalpy calculation is= Enthalpy of Product – Enthalpy of Reactant

  • =[3x(-285.83)+2x(-989.6)]-[(-824.2)+6x(-332.36)
  • =-2836.69+2818.36 KJ/mol
  • = -18.33 KJ/mol

Is HF + Fe2O3 a buffer solution?

HF + Fe2O3 will not form a buffer solution because Fe2O3 acts as a strong base in presence of a weak acid HF. Thus property of a buffer solution is not maintained.

Is HF + Fe2O3 a complete reaction?

HF + Fe2O3 reaction is a complete neutralization reaction as FeF3 is obtained as a salt for this reaction along with water.

Is HF + Fe2O3 an exothermic or endothermic reaction?

HF + Fe2O3 is an exothermic reaction. It is because of the negative value of enthalpy (-18.33 KJ/mol) which means heat is released during the reaction.

Is HF + Fe2O3 a redox reaction?

HF + Fe2O3 is not a redox reaction because the oxidation states of the elements remain same before and after completion of the reaction.

Is HF + Fe2O3 a precipitation reaction?

HF + Fe2O3 is a precipitation reaction since a pale greenish precipitate of FeF3 is obtained after the completion of the reaction.

Is HF + Fe2O3 reversible or irreversible reaction?

HF + Fe2O3 is an irreversible reaction as it is an acid base reaction because FeF3 , that is produced as a salt along with water at the end of the reaction, is slightly soluble in water thus making the reaction irreversible in nature.

Is HF + Fe2O3 displacement reaction?

HF + Fe2O3 is a double displacement reaction, where H of HF is displaced by Fe from Fe2O3 and also O from Fe2O3 is displaced by H of HF. Besides, it is an acid base neutralization reaction which is an example of displacement reactions.


Reaction of hydrofluoric acid with ferrous oxide results in the formation of ferric fluoride as a salt along with water from the acid-base neutralization reaction.

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